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1

Microfluidic platforms for gallium-based liquid metal alloy  

NASA Astrophysics Data System (ADS)

As an alternative to toxic mercury, non-toxic gallium-based liquid metal alloy has been gaining popularity due to its higher thermal and electrical conductivities, and low toxicity along with liquid property. However, it is difficult to handle as the alloy becomes readily oxidized in atmospheric air environment. This instant oxidation causes the gallium-based liquid metal alloy to wet almost any solid surface. Therefore, it has been primarily limited to applications which rely only on its deformability, not on its mobility. In this research, various approaches to mobilize gallium-based liquid metal alloy were investigated. Multi-scale surface patterned with polydimethylsiloxane (PDMS) micro pillar array showed super-lyophobic property against gallium-based liquid metal alloy by minimizing the contact area between the solid surface and the liquid metal, and it was expanded to a three-dimensional tunnel shaped microfluidic channel. Vertically-aligned carbon nanotube forest leads to another promising super-lyophobic surface due to its hierarchical micro/nano scale combined structures and chemical inertness. When the carbon nanotubes were transferred onto flexible PDMS by imprinting, the super-lyophobic property was still maintained even under the mechanical deformation such as stretching and bending. Alternatively, the gallium-based liquid metal can be manipulated by modifying the surface of liquid metal itself. With chemical reaction with HCl 'vapor', the oxidized surface (mainly Ga2O3/Ga2O) of gallium-based liquid metal was converted to GaCl3/InCl 3 resulting in the recovery of non-wetting characteristics. Paper which is intrinsically porous is attractive as a super-lyophobic surface and it was found that hydrochloric acid (HCl) impregnation enhanced the anti-wetting property by the chemical reaction. As another alternative method, by coating the viscoelastic oxidized surface of liquid metal with ferromagnetic materials (CoNiMnP or Fe), it showed non-wetting property and became moveable by applying a magnetic field. Finally, using its metallic and liquid properties, microfluidic-based applications of gallium-based liquid metal alloy such as inkjet printing and reconfigurable photomask were investigated. A clog-free and oxide-free inkjet printing technique was developed by incorporating HCl-impregnated paper as orifice. Inkjet-printed liquid metal line can be used as a metallic interconnect even with significant deformation of the flexible substrate. Additionally, based on its ultraviolet light blocking property, a reconfigurable photolithography using gallium-based liquid metal alloy was demonstrated in a PDMS-based 7-segments microfluidic channel by showing single digit numbers ('0'˜'9') with attainable minimum feature size of 10 microm.

Kim, Daeyoung

2

Aluminum additions in polycrystalline iron-gallium (Galfenol) alloys  

NASA Astrophysics Data System (ADS)

Galfenol alloys show promise as a new magnetically activated smart material based on their unique combination of relatively high magnetostrictive performance and good mechanical robustness. Investigations of aluminum additions to single crystal iron-gallium alloys have been done previously, and the magnetostrictive response seems to follow the rule of mixtures with decreasing saturation magnetostriction with increasing aluminum content. Aluminum is assumed to substitute for Ga directly in the alloy. Directionally solidified polycrystalline Galfenol alloys with aluminum additions were produced to determine the effects on the magnetic properties. Iron-gallium-aluminum alloys were investigated for two primary reasons: (1) Fe-Al alloys are well established and are typically manufactured using conventional thermo-mechanical processing techniques such as rolling; it is anticipated that aluminum additions will aid in the development of Galfenol alloy rolled sheets (2) Gallium prices continue to rise and a cost effective alternative needs to be investigated. Several Fe-Ga-Al alloy compositions were prepared using the Free Stand Zone Melting (FSZM) directional solidification technique. Alloy composition ranges investigated include: Fe 80.5Ga xAl 19.5-x (4.9<=x<=13), Fe 81.6Ga yAl 18.4-y (4.6<=y<=13.8), and Fe 85Ga zAl 15-z (3.75<=z<=11.25). Alloys were studied using EDS (chemistry verification), EBSD (crystallite orientation), and magnetic characterization techniques to determine the effect of aluminum addition on the polycrystalline binary Fe-Ga system. Magnetic properties such as saturation magnetostriction (? sat), piezomagnetic constant (d 33), and relative magnetic permeability (? r) of directionally solidified Fe-Ga-Al polycrystalline alloys will be compared to binary Fe-Ga alloys including investigations into the crystal orientation effects on these properties. Results suggest that up to 50% aluminum can be substituted in the alloy while maintaining considerable saturation magnetostriction, > 200 ppm.

Brooks, M. D.; Summers, E.; Meloy, R.; Mosley, J.

2008-03-01

3

Dynamic property determination of magnetostrictive iron-gallium alloys  

Microsoft Academic Search

Alloys of iron and non-magnetic gallium (of the form Fe1-xGax), collectively referred to as Galfenol, have been shown to exhibit magnetostrictions in excess of 300 ppm under quasi-static magnetic fields [1]. However, to harness the full potential of this material as an actuator, characterization of Galfenol's magneto-mechanical properties under dynamic operating conditions is required. Broadband frequency domain results include strain

Luke M. Twarek; Alison B. Flatau

2005-01-01

4

Fundamental studies of the metallurgical, electrical, and optical properties of gallium phosphide and gallium phosphide alloys  

NASA Technical Reports Server (NTRS)

Abstracts, bibliographic data, oral presentations, and published papers on (1) Diffusion of Sulfur in Gallium Phosphide and Gallium Arsenide, and (2) Properties of Gallium Phosphide Schottky Barrier Rectifiers for Use at High Temperature are presented.

1972-01-01

5

Development and modeling of iron-gallium alloys  

NASA Astrophysics Data System (ADS)

Alloys of iron substituted with non-magnetic gallium (Galfenol) appear promising as mechanically robust actuator/sensing materials. They offer desirable properties including tensile strengths and magnetostrictive strains, respectively, on the order of 100 MPa and 100 x 10-6. To advance the understanding of these materials, this dissertation examines the alloys' magnetic and mechanical response as a function of applied magnetic field, mechanical stress, temperature, stoichiometry and crystallographic morphology. Characterizations of the alloys' single-crystal magneto strictive, elastic and plastic properties are used to facilitate the development and modeling of polycrystalline forms of the material having preferred crystallographic orientations (i.e. texture). The polycrystalline forms have potentially higher production yields and superior mechanical properties over those of single crystals. Irongallium alloys textured by different manufacturing processes reveal which production methods result in the most desirable magnetostrictive and mechanical performance envelopes. Growth and deformation processing techniques such as directional solidification, extrusion, forging and rolling were used to impart a variety of different texture distributions. Single-crystal tensile test were used to determine the material's elastic constants, yield stress, slip systems and their critical resolved shear stress as well as ultimate strength and percent elongation. Observations of the single-crystal alloys' remarkable in-plane auxeticity (or negative Poisson's ratio) and quadratic correlations of the Poisson's ratio magnitude to the level of gallium substitution are reported. Potential applications based on in-plane auxeticity are explored. Elastic properties, as determined from tensile testing on single-crystal specimens, provided the basis for the development and use of a M&barbelow;agnetostrictive M&barbelow;icromechanics F&barbelow;inite-E&barbelow;lement M&barbelow;odel (MMFEM) that captured the coupled magnetic and mechanical behavior of polycrystalline specimens. The MMFEM correctly reflects the bulk magnetostrictive capability of polycrystalline specimens having well-characterized texture distributions and provides a tool for predicting the magnetostrictive performance of textures yet to be produced.

Kellogg, Rick Allen

6

Dynamic property determination of magnetostrictive iron-gallium alloys  

NASA Astrophysics Data System (ADS)

Alloys of iron and non-magnetic gallium (of the form Fe1-xGax), collectively referred to as Galfenol, have been shown to exhibit magnetostrictions in excess of 300 ppm under quasi-static magnetic fields [1]. However, to harness the full potential of this material as an actuator, characterization of Galfenol's magneto-mechanical properties under dynamic operating conditions is required. Broadband frequency domain results include strain per applied magnetic field transfer functions and complex electrical impedance functions. The properties investigated were linear mechanical rod stiffness, magneto-mechanical coupling coefficient, modulus of elasticity, and system structural damping. The samples tested were single-crystal cylindrical Galfenol rods with an atomic percentage of Gallium varying from 18 to 22.5. Some rods were composed of laminated strips of Galfenol to reduce eddy current effects and increase the efficiency of transduction. It was found that lamination did not significantly degrade the stiffness nor increase the structural damping, but did increase the magneto-mechanical coupling coefficient by ~50% over the solid rod for the conditions studied.

Twarek, Luke M.; Flatau, Alison B.

2005-05-01

7

Miniature spherical motor using iron-gallium alloy (Galfenol)  

NASA Astrophysics Data System (ADS)

We propose a miniature spherical motor using iron-gallium alloy (Galfenol). This motor consists of four rods of Galfenol with square cross-section, a wound coil, a permanent magnet, an iron yoke and a spherical rotor placed on the edge of the rods. The magnetomotive force of the magnet provides bias magnetostriction for the rods and an attractive force that maintains the rotor on the rods. When currents of 180 deg phase difference flow in pairs of opposing coils, a torque is exerted on the rotor is by pushing (expansion) and pulling (contraction) of the rods. Rotation about a single axis is realized by a sawtooth current, such that the rotor rotates with slow expansion and slips at the rapid contraction. The motor can be fabricated at small sizes and driven with a low voltage, suitable for application as a microactuator for rotating the camera and mirror in endoscopes.

Ueno, Toshiyuki; Saito, Chihiro; Imaizumi, Nobuo; Higuchi, Toshiro

2008-03-01

8

Galvanic corrosion and cytotoxic effects of amalgam and gallium alloys coupled to titanium.  

PubMed

The aim of this study was to examine and compare the galvanic corrosion of a conventional, a dispersed high-copper, and a palladium-enriched spherical high-copper amalgam and a gallium alloy coupled to titanium in saline and cell culture solutions, and to evaluate the effects of the couples on cultured cells. The potentials and charge transfers between amalgams and titanium were measured by electrochemical corrosion methods. Cytotoxicity of the couples, as indicated by the uptake of neutral red vital stain, was determined in 24-h direct contact human gingival fibroblast cell cultures. Results of this study indicated that before connecting the high-copper amalgams to titanium, the amalgams exhibited more positive potentials which resulted in initial negative charge transfers, i.e. corrosion of titanium. However, this initial corrosion appeared to cause titanium to passivate, and a shift in galvanic currents to positive charge transfers, i.e. corrosion of the amalgam samples. Lower galvanic currents were measured for the amalgam-titanium couples as compared to the gallium alloy-titanium couple. Coupling the conventional or the palladium-enriched high-copper amalgams to titanium did not significantly affect the uptake of neutral red as compared to cells not exposed to any test alloy. However, significant cytotoxic effects were observed when the dispersed-type high-copper amalgam and the gallium alloy were coupled to titanium. Even though the corrosion currents measured for these couples were less than gold alloys coupled to amalgam, these results suggest there is the potential for released galvanic corrosion products to become cytotoxic. These data warrant further investigations into the effects of coupling amalgam and gallium alloys to titanium in the oral environment. PMID:8831065

Bumgardner, J D; Johansson, B I

1996-06-01

9

Czochralski growth of gallium indium antimonide alloy crystals  

SciTech Connect

Attempts were made to grow alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb by the conventional Czochralski process. A transparent furnace was used, with hydrogen purging through the chamber during crystal growth. Single crystal seeds up to about 2 to 5 mole% InSb were grown from seeds of 1 to 2 mole% InSb, which were grown from essentially pure GaSb seeds of the [111] direction. Single crystals were grown with InSb rising from about 2 to 6 mole% at the seed ends to about 14 to 23 mole% InSb at the finish ends. A floating-crucible technique that had been effective in reducing segregation in doped crystals, was used to reduce segregation in Czochralski growth of alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb. Crystals close to the targeted composition of 1 mole% InSb were grown. However, difficulties were encountered in reaching higher targeted InSb concentrations. Crystals about 2 mole% were grown when 4 mole% was targeted. It was observed that mixing occurred between the melts rendering the compositions of the melts; and, hence, the resultant crystal unpredictable. The higher density of the growth melt than that of the replenishing melt could have triggered thermosolutal convection to cause such mixing. It was also observed that the floating crucible stuck to the outer crucible when the liquidus temperature of the replenishing melt was significantly higher than that of the growth melt. The homogeneous Ga{sub 1{minus}x}In{sub x}Sb single crystals were grown successfully by a pressure-differential technique. By separating a quartz tube into an upper chamber for crystal growth and a lower chamber for replenishing. The melts were connected by a capillary tube to suppress mixing between them. A constant pressure differential was maintained between the chambers to keep the growth melt up in the growth chamber. The method was first tested with a low temperature alloy Bi{sub 1{minus}x}Sb{sub x}. Single crystals of Ga{sub 1{minus}x}In{sub x}Sb were grown with uniform compositions up to nearly 5 mole% InSb.

Tsaur, S.C.

1998-02-01

10

Alloying and Structure of Ultrathin Gallium Films on the (111) and (110) Surfaces of Palladium  

PubMed Central

Growth, thermal stability, and structure of ultrathin gallium films on Pd(111) and Pd(110) are investigated by low-energy ion scattering and low-energy electron diffraction. Common to both surface orientations are growth of disordered Ga films at coverages of a few monolayers (T = 150 K), onset of alloy formation at low temperatures (T ? 200 K), and formation of a metastable, mostly disordered 1:1 surface alloy at temperatures around 400–500 K. At higher temperatures a Ga surface fraction of ?0.3 is slightly stabilized on Pd(111), which we suggest to be related to the formation of Pd2Ga bulk-like films. While on Pd(110) only a Pd-up/Ga-down buckled surface was observed, an inversion of buckling was observed on Pd(111) upon heating. Similarities and differences to the related Zn/Pd system are discussed. PMID:24089625

2013-01-01

11

Experimental evidence of Alfvén wave propagation in a Gallium alloy  

NASA Astrophysics Data System (ADS)

Experiments with a liquid metal alloy, Galinstan, are reported and show clear evidence of Alfvén wave propagation as well as resonance of Alfvén modes. Galinstan is liquid at room temperature and, although its electrical conductivity is not as large as that of liquid sodium or NaK, it has still been possible to study Alfvén waves, thanks to the use of intense magnetic fields up to 13 T. The maximal values of Lundquist number, around 60, are similar to that of the reference experimental study by Jameson [J. Fluid Mech. 19, 513 (1964)]. The generation mechanism for Alfvén waves and their reflection is studied carefully. Numerical simulations have been performed and have been able to reproduce the experimental results, despite the fact that the simulated magnetic Prandtl number was much larger than that of Galinstan. An originality of the present study is that a poloidal disturbance (magnetic and velocity fields) is generated, allowing us to track its propagation from outside the conducting domain, hence without interfering.

Alboussière, Thierry; Cardin, Philippe; Debray, François; La Rizza, Patrick; Masson, Jean-Paul; Plunian, Franck; Ribeiro, Adolfo; Schmitt, Denys

2011-09-01

12

Ab initio study of gallium stabilized ?-plutonium alloys and hydrogen-vacancy complexes.  

PubMed

All-electron density functional theory was used to investigate ?-plutonium (?-Pu) alloyed with gallium (Ga) impurities at 3.125, 6.25, 9.375 atomic (at)% Ga concentrations. The results indicated that the lowest energy structure is anti-ferromagnetic, independent of the Ga concentration. At higher Ga concentrations (>3.125?at%), the position of the Ga atoms are separated by four nearest neighbor Pu-Pu shells. The results also showed that the lattice constant contracts with increasing Ga concentration, which is in agreement with experimental data. Furthermore with increasing Ga concentration, the face-centered-cubic structure becomes more stably coupled with increasing short-range disorder. The formation energies show that the alloying process is exothermic, with an energy range of -0.028 to -0.099?eV/atom. The analyses of the partial density of states indicated that the Pu-Ga interactions are dominated by Pu 6d and Ga 4p hybridizations, as well as Ga 4s-4p hybridizations. Finally, the computed formation energies for vacancy and hydrogen-vacancy complexes within the 3.125?at% Ga cell were 1.12?eV (endothermic) and -3.88?eV (exothermic), respectively. In addition, the hydrogen atom prefers to interact much more strongly to the Pu atom than the Ga atom in the hydrogen-vacancy complex. PMID:24832613

Hernandez, Sarah C; Schwartz, Daniel S; Taylor, Christopher D; Ray, Asok K

2014-06-11

13

Micromagnetostrictive vibrator using a U-shaped core of iron-gallium alloy (Galfenol)  

NASA Astrophysics Data System (ADS)

A micromagnetostrictive vibrator using a U-shaped core made of iron-gallium alloy (Galfenol) was investigated. The vibrator consists of a Galfenol core, with a 1mm2 cross section, a length of 5.8mm, and a 0.3mm separation between the prongs of the "U," driving coils, and an iron yoke to close the magnetic loop. The Galfenol vibrator is superior to the PZT type in its high mechanical strength, low drive voltage requirements, and wide temperature operating range, and compared to our previous cylindrical type vibrator has a simpler construction and higher bandwidth. A displacement of 1.2?m (220ppm) was verified for the prototype with a 5.8mm long Galfenol core; the high magnetostriction >200ppm is inherited from the stress-annealed Galfenol. The displacement was also maintained under a 21MPa tensile stress (1.5kg hanging weight). Incorporation of a Nd-B-Fe magnet into the magnetic circuit successfully shifted the operating point to the linear portion of the magnetostrictive curves. This biasing effect is useful in reducing the drive voltage.

Ueno, T.; Higuchi, T.; Saito, C.; Imaizumi, N.; Wun-Fogle, M.

2008-04-01

14

Controlled Electrochemical Synthesis Of Giant Magnetostrictive Iron-Gallium Alloy Thin Films And Nanowires  

NASA Astrophysics Data System (ADS)

Magnetostrictive Galfenol (Fe1-xGax, x = 10%--40%) alloys have generated tremendous interest in recent times because of their potential as functional materials in various micro- and nano-electromechanical systems (MEMS/NEMS)-based transducers and sensors. Among the giant magnetostrictive alloys, Terfenol-D (Tb1-xDyxFe2) has the largest magnetostriction, but its brittle nature limits its applications. In contrast, the next best magnetostrictive alloy, Galfenol, is highly malleable and ductile while having the tensile strength of Iron. Electrochemistry is an economical route to fabricate 'very thick' films (upto several microns) or high-aspect ratio structures like nanowire arrays. However, the highly electropositive nature of gallium makes it very difficult to electrodeposit from aqueous solutions, similar in behavior to other non-ideal elements like molybdenum, phosphorus, tungsten etc. As a result, Fe1-xGa x alloy plating has been severely plagued by non-repeatability in compositions from growth to growth, lack of uniformity in filling of pores when growing nanowires in nanoporous templates, undesired secondary hydrogen evolution reactions etc. In this study, a thorough understanding of the complex interplay between various deposition parameters (pH, overpotential, concentration, hydrodynamic conditions) was achieved, leading to an understanding of the deposition mechanism itself, thus allowing excellent control and ability to tune the alloy compositions. Arrays of nanowires were fabricated with alternating segments of the magnetostrictive alloy Fe1-xGax and Cu in nanoporous anodic aluminum oxide (AAO) templates. A novel rotating disk electrode-template (designed in-house) was used to optimize the nanowire length distributions by controlling the various aspects of electrodeposition like nucleation, kinetics and mass-transfer. Extensive structural characterization was done by X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), and magnetic characterization by vibrating sample magnetometry (VSM). Furthermore, of excellent promise in semiconductor spintronics, the feasibility of fabricating epitaxially nucleated Fe1-xGax thin films on GaAs having the desired (001) texture was demonstrated. Structural characterization using microdiffraction, high resolution ? - 2theta and rocking curve analysis revealed that the films grown on GaAs(001) are highly textured with <001> orientation along the substrate normal, and the texture improved further upon annealing at 300 °C for 2 hours in N2 environment. This was in contrast to films grown on polycrystalline brass substrates which exhibited undesired <011> texture out-of-plane. Rocking curve analysis on Fe1-xGax/GaAs structures further confirmed that the <001> texture in the Fe1-xGax thin film was indeed due to epitaxial nucleation and growth. A non-linear current-voltage plot was obtained for the Fe1-xGax/GaAs Schottky contacts, characteristic of tunneling injection, and showed improved behavior with annealing.

Reddy, Kotha Sai Madhukar

15

Organometallic Vapor-Phase Epitaxial Growth and Characterization of Iii-V Semiconductor Alloys Emitting Visible Light: Gallium Arsenic Phosphide, Gallium Indium Phosphide, and Aluminum Gallium Indium Phosphide  

NASA Astrophysics Data System (ADS)

High band gap III-V semiconductor alloys, GaAs _{rm 1-x}P _{rm x}, Ga_ {rm x}In_{rm 1-x}P, and (Al_{rm x}Ga_{rm 1-x} )_{rm y}In _{rm 1-y}P, have been successfully grown on GaAs substrates using atmospheric pressure organometallic vapor-phase epitaxy (OMVPE). Trimethylgallium (TMGa), trimethylindium (TMIn), and trimethylaluminum (TMAI), were used as group III source materials, and arsine (AsH _3), phosphine (PH_3 ), and tertiarybutylphosphine (TBP) were used as group V source materials. For the growth of GaAs_{rm 1-x}P_{rm x} , strained layer superlattices (SLSs) were used to reduce misfit dislocation density. The grown structure consisted of a 2-?m P compositionally graded layer, a GaAs_{rm 1-y' }P_{rm y'}/GaAs _{rm 1-y}P _{rm y} SLS, and a 1- ?m GaAs_{0.6}P _{0.4} layer. It was found that linear grading gave the lowest dislocation density among the three grading layers investigated: sublinear, hyperlinear, and linear. A novel method, called "overshoot," was developed to prevent the release of residual strain in the 2-?m linearly graded layer. Using the overshoot method and SLSs, GaAs_{0.6 }P_{0.4} with good surface morphology, strong visible photoluminescence(PL) intensity, and a dislocation density of 6.5 times 10^5 cm^ {-2} has been obtained. For growth of GaInP, the effect of growth rate on the properties of the layers was investigated. It was observed that surface morphology degraded, the band gap at 300K decreased by 40meV, and the degree of ordering and size of ordered domains increased when the growth rate was changed from 12 to 4.1 mum/hr. At high growth rates (~12 mum/hr), the 300-K band gap of epilayer had the same values as the layers grown by LPE and was independent of the V/III ratio. The epilayers grown at a rate of 12 mum/hr and a V/III ratio of 148 had PL halfwidths of 35 and 7.2meV at 300K and 10K, respectively, the best reported results to date. A mechanism for the growth rate effect on the properties of OMVPE-grown GaInP is discussed. For the growth of AlGaInP, either PH_3 or TBP was used as the group V source material, respectively. For layers grown using trimethylalkyls and PH_3, excellent surface morphologies were obtained over the entire Al composition range. The 300-K band gap varied with x as 1.9 + 0.6x, consistent with calculated and previous results. The experimental results showed that the minority-carrier lifetime was constant when Al concentration was changed. For layers grown using trimethylalkyls and TBP, the P vapor pressure required was less than that using PH_3 to obtain good surface morphologies. No parasitic reactions were observed between TBP and the trimethylalkyls. However, the PL peak energy for layers grown using TBP did not follow the relation 1.9 + 0.6x. This was explained by a deep donor level, induced by an impurity from the TBP, bound to the X conduction band minimum. It is concluded that TBP is a suitable material to replace PH_3 for OMVPE growth of Al-containing compounds.

Cao, Diansheng

16

Thermodynamics of reaction of praseodymium with gallium-indium eutectic alloy  

NASA Astrophysics Data System (ADS)

Thermodynamic properties of Ga-In eutectic alloys saturated with praseodymium were determined for the first time employing the electromotive force method. The equilibrium potentials of the Pr-In alloys saturated with praseodymium (8.7-12.1 mol.% Pr) and Pr-Ga-In alloys (containing 0.0012-6.71 mol.% Pr) were measured between 573-1073 K. Pr-In alloy containing solid PrIn3 with known thermodynamic properties was used as the reference electrode when measuring the potentials of ternary Pr-In-Ga alloys. Activity, partial and excessive thermodynamic functions of praseodymium in alloys with indium and Ga-In eutectic were calculated. Activity (a), activity coefficients (?) and solubility (X) of praseodymium in the studied temperature range can be expressed by the following equations: lga?-Pr(In) = 4.425 - 11965/T ± 0.026. lg??-Pr(Ga-In) = 5.866 - 14766/T ± 0.190. lg??-Pr(Ga-In) = 2.351 - 9996/T ± 0.39. lg?Pr(Ga-In) = 3.515 - 4770/T ± 0.20.

Melchakov, S. Yu.; Ivanov, V. A.; Yamshchikov, L. F.; Volkovich, V. A.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-06-01

17

Measurement of field-dependence elastic modulus of iron-gallium alloy using tensile test  

SciTech Connect

An experimental approach is used to identify Galfenol material properties under dc magnetic bias fields. Dog-bone-shaped specimens of single crystal Fe{sub 100-x}Ga{sub x}, where 18.6{<=}x{<=}33.2, underwent tensile testing along two crystallographic axis orientations, [110] and [100]. Young's modulus and Poisson's ratio sensitivity to magnetic fields and stoichiometry are investigated. Data are presented that demonstrate the dependence of these properties on applied magnetic-field levels and provide a substantial assessment of the trends in material properties for performance of alloys of different stoichiometries under varied operating conditions.

Yoo, Jin-Hyeong; Flatau, Alison B. [University of Maryland, College Park, Maryland 20742 (United States)

2005-05-15

18

Evaluation of magnetostrictive shunt damper performance using Iron (Fe)-Gallium (Ga) alloy  

NASA Astrophysics Data System (ADS)

This study presents the possibility of dissipating mechanical energy with a proof-of-concept prototype magnetostrictive based shunt circuit using passive electrical components. The device consists of a polycrystalline galfenol (Fe-Ga alloy) strip bonded to a brass cantilever beam. Two brass pieces, each containing a permanent magnet, are used to mass load each end of the beam and to provide a magnetic bias field through the galfenol strip. The voltage induced in an induction coil closely wound around the cantilever beam captures the time rate of change of magnetic flux within the galfenol strip as the beam vibrates. The first bending-mode resonant frequency of the device was 69.42 Hz. To dissipate the electrical voltage from the device, a shunt circuit is attached. The effective mechanical impedance for the magnetostrictive shunt circuit is derived. The shunted model is specialized for two shunt circuits: the case of a resistor and that of a capacitance. The experimental results for both the resistive and capacitance shunt circuits validate the shunted magnetostrictive damping model for couple of cased of resistance and capacitance.

Yoo, JinHyeong; Murray, Andrew; Flatau, Alison B.

2014-04-01

19

Gallium Safety in the Laboratory  

SciTech Connect

A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

Cadwallader, L.C.

2003-05-07

20

Gallium Safety in the Laboratory  

SciTech Connect

A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

Lee C. Cadwallader

2003-06-01

21

Gallium--A smart metal  

USGS Publications Warehouse

Gallium is a soft, silvery metallic element with an atomic number of 31 and the chemical symbol Ga. The French chemist Paul-Emile Lecoq de Boisbaudran discovered gallium in sphalerite (a zinc-sulfide mineral) in 1875 using spectroscopy. He named the element "gallia" after his native land of France (formerly Gaul; in Latin, Gallia). The existence of gallium had been predicted in 1871 by Dmitri Mendeleev, the Russian chemist who published the first periodic table of the elements. Mendeleev noted a gap in his table and named the missing element "eka-aluminum" because he determined that its location was one place away from aluminum in the table. Mendeleev thought that the missing element (gallium) would be very much like aluminum in its chemical properties, and he was right. Solid gallium has a low melting temperature (~29 degrees Celsius, or °C) and an unusually high boiling point (~2,204 °C). Because of these properties, the earliest uses of gallium were in high-temperature thermometers and in designing metal alloys that melt easily. The development of a gallium-based direct band-gap semiconductor in the 1960s led to what is now one of the most well-known applications for gallium-based products--the manufacture of smartphones and data-centric networks.

Foley, Nora; Jaskula, Brian

2013-01-01

22

Development of gallium aluminum phosphide electroluminescent diodes  

NASA Technical Reports Server (NTRS)

Work done on the development of gallium aluminum phosphide alloys for electroluminescent light sources is described. The preparation of this wide band gap semiconductor alloy, its physical properties (particularly the band structure, the electrical characteristics, and the light emitting properties) and work done on the fabrication of diode structures from these alloys are broadly covered.

Chicotka, R. J.; Lorenz, M. R.; Nethercot, A. H.; Pettit, G. D.

1972-01-01

23

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes  

E-print Network

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium properties of liquid gallium and eutectic gallium-indium Phys. Fluids 24, 063101 (2012); 10); 10.1063/1.3670048 Evaluation of gallium-indium alloy as an acoustic couplant for high-impedance, high

Deseri, Luca

24

Gallium complexes and solvent extraction of gallium  

SciTech Connect

This patent describes a process for recovering gallium from aqueous solutions containing gallium which comprises contacting such a solution with an organic solvent containing at least 2% by weight of a water-insoluble N-organo hydroxamic acid having at least about 8 carbon atoms to extract gallium, and separating the gallium loaded organic solvent phase from the aqueous phase.

Coleman, J.P.; Graham, C.R.; Monzyk, B.F.

1988-05-03

25

Gallium: the backbone of the electronics industry  

Microsoft Academic Search

Gallium is a silvery blue and soft metallic element that enjoys vast application in optoelectronics (e.g., LED’s), telecommunication, aerospace, and many commercial and household items such as alloys, computers and DVD’s. Albeit that gallium represents a small annual tonnage of material, its important impact as the backbone of the worldwide electronics sector goes unnoticed by the popularity of key base

R. R. Moskalyk

2003-01-01

26

The role of sulfur alloying in defects and transitions in copper indium gallium diselenide disulfide thin films  

Microsoft Academic Search

The effects of sulfur alloying on the electronic properties of CuIn(SeS) 2 and CuInGa(SeS)2 materials has been investigated using sophisticated junction capacitance techniques including drive-level capacitance profiling and transient photocapacitance and photocurrent spectroscopies. CISSe and CIGSSe materials are used as absorber layers in thin-film photovoltaic devices. By characterizing the electronic properties of these materials we hope to understand how these

Adam Fraser Halverson

2007-01-01

27

Gallium-enhanced phase contrast in atom probe tomography of nanocrystalline and amorphous Al-Mn alloys.  

PubMed

Over a narrow range of composition, electrodeposited Al-Mn alloys transition from a nanocrystalline structure to an amorphous one, passing through an intermediate dual-phase nanocrystal/amorphous structure. Although the structural change is significant, the chemical difference between the phases is subtle. In this study, the solute distribution in these alloys is revealed by developing a method to enhance phase contrast in atom probe tomography (APT). Standard APT data analysis techniques show that Mn distributes uniformly in single phase (nanocrystalline or amorphous) specimens, and despite some slight deviations from randomness, standard methods reveal no convincing evidence of Mn segregation in dual-phase samples either. However, implanted Ga ions deposited during sample preparation by focused ion-beam milling are found to act as chemical markers that preferentially occupy the amorphous phase. This additional information permits more robust identification of the phases and measurement of their compositions. As a result, a weak partitioning tendency of Mn into the amorphous phase (about 2 at%) is discerned in these alloys. PMID:21740869

Ruan, Shiyun; Torres, Karen L; Thompson, Gregory B; Schuh, Christopher A

2011-07-01

28

Bismuth in gallium arsenide: Structural and electronic properties of GaAs{sub 1-x}Bi{sub x} alloys  

SciTech Connect

The structural and electronic properties of cubic GaAs{sub 1-x}Bi{sub x} alloys with bismuth concentration 0.0, 0.25, 0.50, 0.75 and 1.0 are studied using the 'special quasi-random structures' (SQS) approach of Zunger along with the generalized gradient approximation (GGA) and the Engel-Vosko generalized gradient approximation (EV-GGA). The lattice constant, bulk modulus, derivative of bulk modulus and energy gap vary with bismuth concentration nonlinearly. The present calculations show that the band gap decreases substantially with increasing bismuth concentration and that spin-orbit coupling influences the nature of bonding at high Bi concentrations. - Graphical abstract: Bowing effect of spin-orbit split-off band values versus Bi content with and without spin-orbit coupling for GaAs{sub 1-x}Bi{sub x} (at x=0.25, 0.50 and 0.75). Calculations are done with GGA. Highlights: Black-Right-Pointing-Pointer Structural and electronic properties of GaAs{sub 1-x}Bi{sub x} alloys were studied. Black-Right-Pointing-Pointer We present results of lattice constant, energy gap, bulk modulus and derivative. Black-Right-Pointing-Pointer The band gap decreases substantially with increasing Bi concentration. Black-Right-Pointing-Pointer Calculations of the density of states and charge densities are also presented. Black-Right-Pointing-Pointer We have performed calculations without and with spin-orbit coupling.

Reshak, Ali Hussain, E-mail: maalidph@yahoo.co.uk [School of Complex Systems, FFWP-South Bohemia University, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Kamarudin, H. [School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Auluck, S. [National Physical Laboratory Dr. KS Krishnan Marg, New Delhi 110012 (India); Kityk, I.V. [Electrical Engineering Department, Technological University of Czestochowa, Al. Armii Krajowej 17/19, Czestochowa (Poland)

2012-02-15

29

Effects of strain on the optical properties of aluminum indium gallium nitride quaternary alloys and their heterostructures  

NASA Astrophysics Data System (ADS)

AlInGaN quaternary films were grown by atmospheric pressure metalorganic chemical vapor deposition at 875°C using trimethylgallium, trimethylaluminum, trimethylindium, and ammonia. The good optical quality of the quaternary films was revealed by low deep level emissions in the room temperature photoluminescence (PL) spectra for film compositions with up to 11% InN and 26% AlN, simultaneously. With the availability of the quaternary alloy as a barrier material, comprehensive investigations on the effects of strain on the optical properties of InGaN quantum wells are possible by independently varying the lattice constant and band gap of the barrier. A test structure was designed to vary the lattice mismatch induced strain experienced by an AlInGaN/In0.08Ga0.92N/AlInGaN quantum well structure. Utilizing this test structure, the effects of tensile and compressive strain on the optical properties of InGaN quantum well layers were investigated for well widths of 3 nm and 9 nm. Time-resolved PL and temperature dependent PL from 10 K to 300 K was used to investigate recombination behavior. It was found that the radiative recombination rate for unstrained wells much higher than that of strained wells due to the effects of the strain induced piezoelectric field. The rate difference results in higher emission intensity for unstrained 3 nm and 9 nm quantum wells than for their strained counterparts. It was found that the activation energy for non-radiative losses was a strong function of strain. For 3 nm wells, the activation energy was 37.7, 18, and 22.1 meV for wells under tensile, zero, and compressive strain respectively. A similar strain dependence trend was observed for the 9 nm wells. Evidence that recombination is strongly influenced by transitions from localized states corresponding to compositional fluctuations is provided by the energy dependence of PL lifetime, the peak emission energy dependence on temperature, and temperature dependence of PL spectral shapes. Furthermore, the energetic depth of the localizing potentials, and hence the nature of the compositional fluctuations, are a strong function of strain. The potential fluctuations are smallest for the unstrained wells and increase as compressive or tensile strain increases.

Aumer, Michael Edward

30

Compatibility of ITER candidate structural materials with static gallium  

SciTech Connect

Tests were conducted on the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor, e.g., Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy, as well as Armco iron, Nickel 270, and pure chromium. Type 316 stainless steel is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400{degrees}C, corrosion rates are {approx}4.0, 0.5, and 0.03 mm/yr for type 316 SS, Inconel 625, and Nb-5 Mo- 1 Zr alloy, respectively. The pure metals react rapidly with gallium. In contrast to findings in earlier studies, pure iron shows greater corrosion than nickel. The corrosion rates at 400{degrees}C are {ge}88 and 18 mm/yr, respectively, for Armco iron and Nickel 270. The results indicate that at temperatures up to 400{degrees}C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The solubility data for pure metals and oxygen in gallium are reviewed. The physical, chemical, and radioactive properties of gallium are also presented. The supply and availability of gallium, as well as price predictions through the year 2020, are summarized.

Luebbers, P.R.; Michaud, W.F.; Chopra, O.K.

1993-12-01

31

Short communication Gallium and oxygen accumulations on gallium nitride surfaces  

E-print Network

Short communication Gallium and oxygen accumulations on gallium nitride surfaces following argon Available online 17 April 2004 Abstract Metallic gallium was observed on the surfaces of GaN commercial rights reserved. Keywords: Gallium nitride; Argon ion milling; Ultra-high vacuum 1. Introduction Gallium

Timmers, Heiko

32

Gallium nitride optoelectronic devices  

NASA Technical Reports Server (NTRS)

The growth of bulk gallium nitride crystals was achieved by the ammonolysis of gallium monochloride. Gallium nitride single crystals up to 2.5 x 0.5 cm in size were produced. The crystals are suitable as substrates for the epitaxial growth of gallium nitride. The epitaxial growth of gallium nitride on sapphire substrates with main faces of (0001) and (1T02) orientations was achieved by the ammonolysis of gallium monochloride in a gas flow system. The grown layers had electron concentrations in the range of 1 to 3 x 10 to the 19th power/cu cm and Hall mobilities in the range of 50 to 100 sq cm/v/sec at room temperature.

Chu, T. L.; Chu, S. S.

1972-01-01

33

Thermodynamic properties of uranium in Ga-In based alloys  

NASA Astrophysics Data System (ADS)

Activity of uranium was determined in gallium, indium and gallium-indium eutectic (21.8 wt.% In) based alloys between 573 and 1073 K employing the electromotive force method. In two-phase U-Ga-In alloys, uranium forms the intermetallic compound UGa3. Activity coefficients and solubility of uranium in Ga-In eutectic were also determined in the same temperature range. Partial thermodynamic functions of ?-U in saturated alloys with gallium, indium and Ga-In eutectic were calculated.

Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Melchakov, S. Yu; Shchetinskiy, A. V.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-07-01

34

Preventing Supercooling Of Gallium  

NASA Technical Reports Server (NTRS)

Principle of heterogeneous nucleation exploited to prevent gallium from supercooling, enabling its use as heat-storage material that crystallizes reproducibly at its freezing or melting temperature of 29 to 30 degrees C. In original intended application, gallium used as heat-storage material in gloves of space suits. Terrestrial application lies in preparation of freezing-temperature reference samples for laboratories. Principle of heterogeneous nucleation also exploited similarly in heat pipes filled with sodium.

Massucco, Arthur A.; Wenghoefer, Hans M.; Wilkins, Ronnie

1994-01-01

35

Visible light electroluminescent diodes of indium-gallium phosphide  

NASA Technical Reports Server (NTRS)

Vapor deposition and acceptor impurity diffusion techniques are used to prepare indium-gallium phosphide junctions. Certain problems in preparation are overcome by altering gas flow conditions and by increasing the concentration of phosphine in the gas. A general formula is given for the alloy's composition.

Clough, R.; Richman, D.; Tietjen, J.

1970-01-01

36

Optical Properties and Electronic Structures of d- and F-Electron Metals and Alloys, Silver-Indium Nickel - GOLD-GALLIUM(2), PLATINUM-GALLIUM(2), - - Cobalt-Aluminum CERIUM-TIN(3), and LANTHANUM-TIN(3)  

NASA Astrophysics Data System (ADS)

Optical properties and electronic structures of disordered Ag_{1-x}In_ {x} (x = 0.0, 0.04, 0.08, 0.12) and Ni_{1-x}Cu_{x }(x = 0.0, 0.1, 0.3, 0.4) alloys and ordered AuGa_2, PtGa _2, beta^' -NiAl, beta^' -CoAl, CeSn_3, and LaSn_3 have been studied. The complex dielectric functions have been determined for Ag_{1-x}In _{x},Ni_{1-x}Cu_ {x},AuGa_2, and PtGa_2 in the 1.2-5.5 eV region and for CeSn_3 and LaSn_3 in the 1.5-4.5 eV region using spectroscopic ellipsometry. Self-consistent relativistic band calculations using the linearized-augmented -plane-wave method have been performed for AuGa _2, PtGa_2,beta^' -CoAl, CeSn_3, and LaSn_3 to interpret the experimental optical spectra. In Ag_{1-x}In_{x} , the intraband scattering rate increases with increasing In concentration in the low-energy region (<3.5 eV). As the In concentration increases, the onset energy of the L_3to L_sp{2}{'}( E_{F}) transitions, 4.03 eV for pure Ag, shifts to higher energies, while that of the L_sp{2}{'}(E _{F}) to L_1 transitions, 3.87 eV for pure Ag, shifts to lower energies. This is only partly attributable to the rise of the Fermi level E_{F} caused by an increase in the average number of electrons per atom due to the In solute and to the narrowing of the Ag 4d-bands. The L_1-band may also lower as In is added. In Ni_{1-x}Cu_ {x}, the 4.7-eV edge (from transitions between the s-d-hybridized bands well below E_ {F} and the s-p-like bands above E _{F}, e.g., X_1 to X_sp{4}{'} ) shifts to higher energies, while the 1.5-eV edge (from transitions between a p-like band below E _{F} and a d-band above E _{F}, e.g., L_sp {2}{'} to L_3) remains at the same energy as the Cu concentration increases. A structure grows in the (2-3)-eV region as Cu is added, and it is interpreted as being due to transitions between the localized Cu subbands. For AuGa_2 and PtGa _2, both compounds show interband absorption at low photon energies (<1.3 eV). The interband absorption for AuGa_2 is strong at about 2 eV while that for PtGa_2 shows a broad structure in the range 2.5-4.5 eV, with a shoulder at 3.3 eV. The observed interband features in the imaginary parts of the complex dielectric functions epsilon_2 can be interpreted in terms of band calculational results. For beta ^'-NiAl and CoAl all of the structures found in the optical spectra of both compounds involve states with some Ni/Co d-character in both the initial and the final states of the transitions. A self-energy correction for the excitation spectrum has been used for beta^' -CoAl to improve the agreement. The optical conductivities of CeSn_3 and LaSn _3 show structures due to interband absorption at about 2 and 3 eV, which are mostly due to transitions between band-like Ce/La d- and f-states. The larger strengths of the structures in CeSn_3 than in LaSn_3 may be due to the existence of more f-character near E_{F} in CeSn_3 than in LaSn _3.

Kim, Kwang Joo

1990-01-01

37

Non-Invasive Drosophila ECG Recording by Using Eutectic Gallium-Indium Alloy Electrode: A Feasible Tool for Future Research on the Molecular Mechanisms Involved in Cardiac Arrhythmia  

PubMed Central

Background Drosophila heart tube is a feasible model for cardiac physiological research. However, obtaining Drosophila electrocardiograms (ECGs) is difficult, due to the weak signals and limited contact area to apply electrodes. This paper presents a non-invasive Gallium-Indium (GaIn) based recording system for Drosophila ECG measurement, providing the heart rate and heartbeat features to be observed. This novel, high-signal-quality system prolongs the recording time of insect ECGs, and provides a feasible platform for research on the molecular mechanisms involved in cardiovascular diseases. Methods In this study, two types of electrode, tungsten needle probes and GaIn electrodes, were used respectively to noiselessly conduct invasive and noninvasive ECG recordings of Drosophila. To further analyze electrode properties, circuit models were established and simulated. By using electromagnetic shielded heart signal acquiring system, consisted of analog amplification and digital filtering, the ECG signals of three phenotypes that have different heart functions were recorded without dissection. Results and Discussion The ECG waveforms of different phenotypes of Drosophila recorded invasively and repeatedly with n value (n>5) performed obvious difference in heart rate. In long period ECG recordings, non-invasive method implemented by GaIn electrodes acts relatively stable in both amplitude and period. To analyze GaIn electrode, the correctness of GaIn electrode model established by this paper was validated, presenting accuracy, stability, and reliability. Conclusions Noninvasive ECG recording by GaIn electrodes was presented for recording Drosophila pupae ECG signals within a limited contact area and signal strength. Thus, the observation of ECG changes in normal and SERCA-depleted Drosophila over an extended period is feasible. This method prolongs insect survival time while conserving major ECG features, and provides a platform for electrophysiological signal research on the molecular mechanism involved in cardiac arrhythmia, as well as research related to drug screening and development. PMID:25226390

Kuo, Po-Hung; Tzeng, Te-Hsuen; Huang, Yi-Chun; Chen, Yu-Hao; Chang, Yi-Chung; Ho, Yi-Lwun; Wu, June-Tai; Lee, Hsiu-Hsian; Lai, Po-Jung; Liu, Kwei-Yan; Cheng, Ya-Chen; Lu, Shey-Shi

2014-01-01

38

Magnetostriction and Magnetic Heterogeneities in Iron-Gallium  

SciTech Connect

Iron-gallium alloys Fe{sub 1-x}Ga{sub x} exhibit an exceptional increase in magnetostriction with gallium content. We present small-angle neutron scattering investigations on a Fe{sub 0.81}Ga{sub 0.19} single crystal. We uncover heterogeneities with an average spacing of 15 nm and with magnetizations distinct from the matrix. The moments in and around the heterogeneities are observed to reorient with an applied magnetic field or mechanical strain. We discuss the possible roles played by nanoscale magnetic heterogeneities in the mechanism for magnetostriction in this material.

Laver, M. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH 5232 Villigen (Switzerland); Materials Research Division, Risoe DTU, Technical University of Denmark, DK-4000 Roskilde (Denmark); Nano-Science Center, Niels Bohr Institute, University of Copenhagen, DK-2100 Koebenhavn (Denmark); Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742 (United States); Mudivarthi, C.; Cullen, J. R.; Wuttig, M. [Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742 (United States); Flatau, A. B. [Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742 (United States); Department of Aerospace Engineering, University of Maryland, College Park, Maryland 20742 (United States); Chen, W.-C. [NIST Center for Neutron Research (NCNR), Gaithersburg, Maryland 20899 (United States); Indiana University, Bloomington, Indiana 47408 (United States); Watson, S. M. [NIST Center for Neutron Research (NCNR), Gaithersburg, Maryland 20899 (United States)

2010-07-09

39

Metal Contacts to Gallium Arsenide.  

NASA Astrophysics Data System (ADS)

While various high performance devices fabricated from the gallium arsenide (GaAs) and related materials have generated considerable interest, metallization are fundamental components to all semiconductor devices and integrated circuits. The essential roles of metallization systems are providing the desired electrical paths between the active region of the semiconductor and the external circuits through the metal interconnections and contacts. In this work, in-situ clean of native oxide, high temperature n-type, low temperature n-type and low temperature p-type ohmic metal systems have been studied. Argon ion mill was used to remove the native oxide prior to metal deposition. For high temperature process n-type GaAs ohmic contacts, Tungsten (W) and Tungsten Silicide (WSi) were used with an epitaxial grown graded Indium Gallium Arsenide (InGaAs) layer (0.2 eV) on GaAs. In addition, refractory metals, Molybdenum (Mo), was incorporated in the Gold-Germanium (AuGe) based on n-type GaAs ohmic contacts to replace conventional silver as barrier to prevent the reaction between ohmic metal and chlorine based plasma as well as the ohmic metallization intermixing which degrades the device performance. Finally, Indium/Gold-Beryllium (In/Au-Be) alloy has been developed as an ohmic contact for p-type GaAs to reduce the contact resistance. The Fermi-level pinning of GaAs has been dominated by the surface states. The Schottky barrier height of metal contacts are about 0.8 V regardless of the metal systems. By using p-n junction approach, barrier height of pulsed C-doped layers was achieved as high as 1.4 V. Arsenic implantation into GaAs method was also used to enhance the barrier height of 1.6 V.

Ren, Fan

1991-07-01

40

Zinc and gallium diffusion in gallium antimonide  

NASA Astrophysics Data System (ADS)

Extrinsic diffusion of zinc (Zn) in gallium antimonide (GaSb) under Ga-rich conditions was analyzed on the basis of the kick-out and the dissociative diffusion mechanism. Accurate modeling of the experimental profiles by means of continuum theoretical calculations reveals that Zn diffusion proceeds via singly positively charged Zn interstitials (Zni+) . The changeover of Zni+ to substitutional gallium (Ga) sites, thereby forming the acceptor dopant ZnGa- , is concluded to be mainly mediated by neutral IGa0 and singly positively charged Ga interstitials IGa+ via the kick-out mechanism. Fitting of the Zn profiles provides the reduced Zni+ -mediated Zn diffusion coefficient and the relative contributions of IGa0 and IGa+ to Ga diffusion. These contributions to Ga diffusion are lower than the directly measured Ga diffusion coefficient, which indicates that Ga diffusion in GaSb is rather mediated by Ga vacancies than by Ga interstitials even under Ga-rich conditions. This finding supports the transformation reaction between native point defects in GaSb that was previously proposed to explain the Ga-vacancy-mediated diffusion of Ga in GaSb under Ga-rich conditions [H. Bracht Nature (London) 408, 69 (2000)].

Sunder, Kirsten; Bracht, Hartmut; Nicols, Samuel P.; Haller, Eugene E.

2007-06-01

41

Designing Asynchronous Circuits in Gallium Arsenide  

E-print Network

Designing Asynchronous Circuits in Gallium Arsenide Jos'e A. Tierno Department of Computer Science.1 Asynchronous circuits : : : : : : : : : : : : : : : : : : : : : : : 4 1.2 Gallium Arsenide : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 6 1.5 Outline of this Thesis : : : : : : : : : : : : : : : : : : : : : : : 6 2 Gallium Arsenide

Martin, Alain

42

Design System for Locally Fabricated Gallium Arsenide  

E-print Network

Design System for Locally Fabricated Gallium Arsenide Digital Integrated Circuits by Anthony Edward, 26 November, 1990 © Anthony Parker 1990 Gallium Arsenide Digital Integrated Circuits Project System for Locally Fabricated Gallium Arsenide Digital Integrated Circuits A thesis submitted to Sydney

43

Gallium-containing anticancer compounds  

PubMed Central

There is an ever pressing need to develop new drugs for the treatment of cancer. Gallium nitrate, a group IIIa metal salt, inhibits the proliferation of tumor cells in vitro and in vivo and has shown activity against non-Hodgkin’s lymphoma and bladder cancer in clinical trials. Gallium can function as an iron mimetic and perturb iron-dependent proliferation and other iron-related processes in tumor cells. Gallium nitrate lacks cross resistance with conventional chemotherapeutic drugs and is not myelosuppressive; it can be used when other drugs have failed or when the blood count is low. Given the therapeutic potential of gallium, newer generations of gallium compounds are now in various phases of preclinical and clinical development. These compounds hold the promise of greater anti-tumor activity against a broader spectrum of cancers. The development of gallium compounds for cancer treatment and their mechanisms of action will be discussed. PMID:22800370

Chitambar, Christopher R

2013-01-01

44

Compatibility of ITER candidate materials with static gallium  

SciTech Connect

Corrosion tests have been conducted to determine the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor (ITER) first wall/blanket systems, e.g., Type 316 stainless steel (SS), Inconel 625, and Nb-5 Mo-1 Zr. The results indicate that Type 316 SS is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400 C, corrosion rates for Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy are {approx} 4.0, 0.5, and 0.03 mm/yr, respectively. Iron, nickel, and chromium react rapidly with gallium. Iron shows greater corrosion than nickel at 400 C ({ge} 88 and 18 mm/yr, respectively). The present study indicates that at temperatures up to 400 C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The growth of intermetallic compounds may control the overall rate of corrosion.

Luebbers, P.R.; Chopra, O.K. [Argonne National Lab., IL (United States). Energy Technology Div.

1995-09-01

45

Polymorphism of Ga-In alloys in nanoconfinement conditions  

NASA Astrophysics Data System (ADS)

The results of acoustic investigations of the melting and crystallization of indium-gallium alloys of different compositions embedded in porous glass matrices with a pore size of 18 nm are presented. It was shown that the formation of the ? and ? crystalline modifications of gallium is possible depending on the alloy composition in nanopores. The fraction of ?-Ga increased as the indium concentration in the alloy increased. Stabilization of ?-Ga in conditions of confined geometry was revealed. Broadening of the melting region of the ? phase of gallium and narrowing of the melting region of ?-Ga, as compared with the corresponding bulk alloys, were observed.

Latysheva, E. N.; Pirozerskii, A. L.; Charnaya, E. V.; Kumzerov, Yu. A.; Fokin, A. V.; Nedbai, A. I.; Bugaev, A. S.

2015-01-01

46

Alloy  

NASA Astrophysics Data System (ADS)

The Mg98.5Gd1Zn0.5 alloy produced by a powder metallurgy route was studied and compared with the same alloy produced by extrusion of ingots. Atomized powders were cold compacted and extruded at 623 K and 673 K (350 °C and 400 °C). The microstructure of extruded materials was characterized by ?-Mg grains, and Mg3Gd and 14H-LPSO particles located at grain boundaries. Grain size decreased from 6.8 ?m in the extruded ingot, down to 1.6 ?m for powders extruded at 623 K (350 °C). Grain refinement resulted in an increase in mechanical properties at room and high temperatures. Moreover, at high temperatures the PM alloy showed superplasticity at high strain rates, with elongations to failure up to 700 pct.

Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

2014-07-01

47

Oxidative dissolution of gallium arsenide and separation of gallium from arsenic  

SciTech Connect

The method of dissociating gallium arsenide into a gallium-containing component and an arsenic-containing component, is described which comprises contacting the gallium arsenide with an oxidizing agent and a liquid comprising hydroxamic acid to convert the gallium to a gallium-hydroxamic acid complex and to oxidize the arsenic to a positive valence state.

Coleman, J.P.; Monzyk, B.F.

1988-07-26

48

Effect of oxidation on the mechanical properties of liquid gallium and eutectic gallium-indium  

E-print Network

Effect of oxidation on the mechanical properties of liquid gallium and eutectic gallium-indium Qin of oxidation on the mechanical properties of liquid gallium and eutectic gallium-indium Qin Xu,1 Nikolai by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium

Brown, Eric

49

Fabrication of Aluminum Gallium Nitride/Gallium Nitride MESFET And It's Applications in Biosensing  

NASA Astrophysics Data System (ADS)

Gallium Nitride has been researched extensively for the past three decades for its application in Light Emitting Diodes (LED's), power devices and UV photodetectors. With the recent developments in crystal growth technology and the ability to control the doping there has been an increased interest in heterostructures formed between Gallium nitride and it's alloy Aluminium Gallium Nitride. These heterostructures due to the combined effect of spontaneous and piezoelectric effect can form a high density and a high mobility electron gas channel without any intentional doping. This high density electron gas makes these heterostructures ideal to be used as sensors. Gallium Nitride is also chemically very stable. Detection of biomolecules in a fast and reliable manner is very important in the areas of food safety and medical research. For biomolecular detection it is paramount to have a robust binding of the probes on the sensor surface. Therefore, in this dissertation, the fabrication and application of the AlGaN/GaN heterostructures as biological sensors for the detection of DNA and Organophosphate hydrolase enzyme is discussed. In order to use these AlGaN/GaN heterostructures as biological sensors capable of working in a liquid environment photodefinable polydimethyl-siloxane is used as an encapsulant. The immobilization conditions for a robust binding of thiolated DNA and the catalytic receptor enzyme organophosphate hydrolase on gold surfaces is developed with the help of X-ray photoelectron spectroscopy. DNA and OPH are detected by measuring the change in the drain current of the device as a function of time.

Alur, Siddharth

50

Sputtering of tin and gallium-tin clusters  

SciTech Connect

Tin and gallium-tin clusters have been produced by 4 keV Ar{sup +} ion bombardment of polycrystalline tin and the gallium-tin eutectic alloy and analyzed by time-of-flight mass spectrometry. The sputtered neutral species were photoionized with 193 nm (6.4 eV) excimer laser light. Neutral tin clusters containing up to 10 atoms and mixed gallium-tin clusters Ga{sub (n-m)}Sn{sub m} with n {<=} 4 for the neutrals and N {<=} 3 for the sputtered ionic species have been detected. Laser power density dependent intensity measurements, relative yields, and kinetic energy distributions have been measured. The abundance distributions of the mixed clusters have been found to be nonstatistical due to significant differences in the ionization efficiencies for clusters with equal nuclearity but different number of tin atoms. The results indicate that Ga{sub 2}Sn and Ga{sub 3}Sn like the all-gallium clusters have ionization potentials below 6.4 eV. In the case of Sn{sub 5}, Sn{sub 6}, GaSn and Ga{sub (n-m)}Sn{sub m} clusters with n=2 to 4 and m>1, the authors detect species that have sufficient internal energy to be one photon ionized despite ionization potentials that are higher 6.4 eV. The tin atom signal that is detected can be attributed to photofragmentation of dimers for both sputtering from polycrystalline tin and from the gallium-tin eutectic alloy.

Lill, T.; Calaway, W.F.; Ma, Z.; Pellin, M.J.

1994-08-01

51

Solar Abundance of Gallium  

PubMed Central

The spectral region around the ?4172 Å resonance line of gallium has been synthesized at disk positions ? = 1.0, 0.5, and 0.3. The center-limb variation can be reproduced by Elste's semiempirical model if a macroturbulent smearing of the emergent spectrum due to mass motions with mean velocity decreasing with altitude are introduced. The abundance of Ga derived from disk position ? = 1 is found to be log [N(Ga)/N(H)] + 12 = 2.80. PMID:16578709

Ross, John; Aller, Lawrence

1970-01-01

52

Gallium phosphide energy converters  

NASA Technical Reports Server (NTRS)

Betavoltaic power supplies based on gallium phosphide can supply long term low-level power with high reliability. Results are presented for GaP devices powered by Ni-63 and tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/cm(exp 2) have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. A small demonstration system has been assembled that generates and stores enough electricity to light up an LED.

Sims, P. E.; DiNetta, Louis C.; DuganCavanagh, K.; Goetz, M. A.

1996-01-01

53

Gallium Arsenide Domino Circuit  

NASA Technical Reports Server (NTRS)

Advantages include reduced power and high speed. Experimental gallium arsenide field-effect-transistor (FET) domino circuit replicated in large numbers for use in dynamic-logic systems. Name of circuit denotes mode of operation, which logic signals propagate from each stage to next when successive stages operated at slightly staggered clock cycles, in manner reminiscent of dominoes falling in a row. Building block of domino circuit includes input, inverter, and level-shifting substages. Combinational logic executed in input substage. During low half of clock cycle, result of logic operation transmitted to following stage.

Yang, Long; Long, Stephen I.

1990-01-01

54

The interaction of gold with gallium arsenide  

NASA Technical Reports Server (NTRS)

Gold and gold-based alloys, commonly used as solar-cell contact materials, are known to react readily with gallium arsenide. Experiments designed to identify the mechanisms involved in these GaAs-metal interactions have yielded several interesting results. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are also explained by invoking this mechanism.

Weizer, Victor G.; Fatemi, Navid S.

1988-01-01

55

Contact formation in gallium arsenide solar cells  

NASA Technical Reports Server (NTRS)

Gold and gold-based alloys, commonly used as solar cell contact materials, are known to react readily with gallium arsenide. Experiments were performed to identify the mechanisms involved in these GaAs-metal interactions. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are explained by invoking this mechanism.

Weizer, Victor G.; Fatemi, Navid S.

1988-01-01

56

GALLIUM--1997 29.1 By Deborah A. Kramer  

E-print Network

GALLIUM--1997 29.1 GALLIUM By Deborah A. Kramer Gallium demand in the United States was supplied by imports, primarily high-purity gallium from France and low-purity material from Russia. Optoelectronic devices manufactured from gallium arsenide (GaAs) continued to be the principal use for gallium. Increased

57

Simulating the Atomic Assembly of Gallium Arsenide  

E-print Network

Simulating the Atomic Assembly of Gallium Arsenide A Dissertation Presented to the Faculty with gallium-rich GaAs (001) surfaces indicate a high sticking probability for SW potentials. This is in good an orientation dependence. Atomic processes responsible for the formation of the gallium vacancy defects were

Wadley, Haydn

58

Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium  

E-print Network

Liquid metals exhibit remarkable mechanical properties, in particular large surface tension and low viscosity. However, these properties are greatly affected by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium (Ga) and a eutectic gallium-indium alloy (eGaIn) while controlling such oxidation by surrounding the metal with an acid bath of variable concentration. Rheometry measurements reveal a yield stress directly attributable to an oxide skin that obscures the intrinsic behavior of the liquid metals. We demonstrate how the intrinsic viscosity can be obtained with precision through a scaling technique that collapses low- and high-Reynolds number data. Measuring surface tension with a pendant drop method, we show that the oxide skin generates a surface stress that mimics surface tension and develop a simple model to relate this to the yield stress obtained from rheometry. We find that yield stress, surface tension, and contact angle all transition from solid-like to liquid behavior at the same critical acid concentration, thereby quantitatively confirming that the wettability of these liquid metals is due to the oxide skin.

Qin Xu; Nikolai Qudalov; Qiti Guo; Heinrich Jaeger; Eric Brown

2012-01-23

59

Gallium phosphide energy converters  

NASA Technical Reports Server (NTRS)

Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

1995-01-01

60

Medical Applications and Toxicities of Gallium Compounds  

PubMed Central

Over the past two to three decades, gallium compounds have gained importance in the fields of medicine and electronics. In clinical medicine, radioactive gallium and stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism. In addition, gallium compounds have displayed anti-inflammatory and immunosuppressive activity in animal models of human disease while more recent studies have shown that gallium compounds may function as antimicrobial agents against certain pathogens. In a totally different realm, the chemical properties of gallium arsenide have led to its use in the semiconductor industry. Gallium compounds, whether used medically or in the electronics field, have toxicities. Patients receiving gallium nitrate for the treatment of various diseases may benefit from such therapy, but knowledge of the therapeutic index of this drug is necessary to avoid clinical toxicities. Animals exposed to gallium arsenide display toxicities in certain organ systems suggesting that environmental risks may exist for individuals exposed to this compound in the workplace. Although the arsenic moiety of gallium arsenide appears to be mainly responsible for its pulmonary toxicity, gallium may contribute to some of the detrimental effects in other organs. The use of older and newer gallium compounds in clinical medicine may be advanced by a better understanding of their mechanisms of action, drug resistance, pharmacology, and side-effects. This review will discuss the medical applications of gallium and its mechanisms of action, the newer gallium compounds and future directions for development, and the toxicities of gallium compounds in current use. PMID:20623028

Chitambar, Christopher R.

2010-01-01

61

Gallium and Reactor Neutrino Anomalies  

NASA Astrophysics Data System (ADS)

The observed deficit in the Gallium radioactive source experiments may be interpreted as a possible indication of active-sterile ? mixing. In the effective framework of two-neutrino mixing we obtain sin2??0.03 and ?m?0.1 eV. The compatibility of this result with the data of the Bugey reactor ? disappearance experiments is studied. It is found that the Bugey data present a hint of neutrino oscillations with 0.02?sin2??0.08 and ?m?1.8 eV, which is compatible with the Gallium allowed region of the mixing parameters. This hint persists in the combined analysis of Gallium, Bugey, and Chooz data.

Acero, M. A.; Giunti, C.; Laveder, M.

2009-03-01

62

Mineral resource of the month: gallium  

USGS Publications Warehouse

The metal element gallium occurs in very small concentrations in rocks and ores of other metals — native gallium is not known. As society gets more and more high-tech, gallium becomes more useful. Gallium is one of only five metals that are liquid at or close to room temperature. It has one of the longest liquid ranges of any metal (29.8 degrees Celsius to 2204 degrees Celsius) and has a low vapor pressure even at high temperatures. Ultra-pure gallium has a brilliant silvery appearance, and the solid metal exhibits conchoidal fracture similar to glass.

Jaskula, Brian

2009-01-01

63

Potential effects of gallium on cladding materials  

SciTech Connect

This paper identifies and examines issues concerning the incorporation of gallium in weapons derived plutonium in light water reactor (LWR) MOX fuels. Particular attention is given to the more likely effects of the gallium on the behavior of the cladding material. The chemistry of weapons grade (WG) MOX, including possible consequences of gallium within plutonium agglomerates, was assessed. Based on the calculated oxidation potentials of MOX fuel, the effect that gallium may have on reactions involving fission products and possible impact on cladding performance were postulated. Gallium transport mechanisms are discussed. With an understanding of oxidation potentials and assumptions of mechanisms for gallium transport, possible effects of gallium on corrosion of cladding were evaluated. Potential and unresolved issues and suggested research and development (R and D) required to provide missing information are presented.

Wilson, D.F.; Beahm, E.C.; Besmann, T.M.; DeVan, J.H.; DiStefano, J.R.; Gat, U.; Greene, S.R.; Rittenhouse, P.L.; Worley, B.A.

1997-10-01

64

Renal amyloidosis. Evaluation by gallium imaging  

SciTech Connect

A study has been performed to evaluate the efficacy of gallium imaging in the detection of renal amyloidosis. Ten of the 11 patients who had biopsy-proven renal amyloidosis demonstrated marked uptake in both kidneys. One patient revealed moderate gallium uptake in his kidneys. None of the patients had underlying renal or extrarenal pathology other than amyloidosis, which could account for renal gallium uptake (renal infection, neoplasm, hepatic failure or frequent blood transfusions). Four patients also had extrarenal foci of abnormal gallium uptake, suggesting other sites of amyloid deposits. Our data strongly suggest that gallium imaging has a high sensitivity for detection of renal amyloidosis. Its specificity is enhanced significantly by careful review of the clinical history to exclude other known causes of renal gallium uptake. Potentially, gallium imaging may be used to monitor the progress of patients under experimental therapy.

Lee, V.W.; Skinner, M.; Cohen, A.S.; Ngai, S.; Peng, T.T.

1986-09-01

65

GALLIUM--1999 29.1 By Deborah A. Kramer  

E-print Network

GALLIUM--1999 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared by Carolyn F. Crews, statistical assistant. Gallium demand in the United States was satisfied by imports% of gallium consumed in the United States was in the form of gallium arsenide (GaAs). Analog integrated

66

A study of the applicability of gallium arsenide and silicon carbide as aerospace sensor materials  

NASA Technical Reports Server (NTRS)

Most of the piezoresistive sensors, to date, are made of silicon and germanium. Unfortunately, such materials are severly restricted in high temperature environments. By comparing the effects of temperature on the impurity concentrations and piezoresistive coefficients of silicon, gallium arsenide, and silicon carbide, it is being determined if gallium arsenide and silicon carbide are better suited materials for piezoresistive sensors in high temperature environments. The results show that the melting point for gallium arsenide prevents it from solely being used in high temperature situations, however, when used in the alloy Al(x)Ga(1-x)As, not only the advantage of the wider energy band gas is obtained, but also the higher desire melting temperature. Silicon carbide, with its wide energy band gap and higher melting temperature suggests promise as a high temperature piezoresistive sensor.

Hurley, John S.

1990-01-01

67

P-type gallium nitride  

DOEpatents

Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5.times.10.sup.11 /cm.sup.3 and hole mobilities of about 500 cm.sup.2 /V-sec, measured at 250.degree. K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al.

Rubin, Michael (Berkeley, CA); Newman, Nathan (Montara, CA); Fu, Tracy (Berkeley, CA); Ross, Jennifer (Pleasanton, CA); Chan, James (Berkeley, CA)

1997-01-01

68

P-type gallium nitride  

DOEpatents

Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5{times}10{sup 11} /cm{sup 3} and hole mobilities of about 500 cm{sup 2} /V-sec, measured at 250 K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al. 9 figs.

Rubin, M.; Newman, N.; Fu, T.; Ross, J.; Chan, J.

1997-08-12

69

Liquid gallium rotary electric contract  

NASA Technical Reports Server (NTRS)

Due to its low vapor pressure, gallium, when substituted for mercury in a liquid slip ring system, transmits substantial amounts of electrical current to rotating components in an ultrahigh vacuum. It features low electrical loss, little or no wear, and long maintenance-free life.

Przybyszewski, J. S.

1969-01-01

70

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary (crude, unrefined) gallium was recovered in 2013. Globally,  

E-print Network

58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary (crude, unrefined) gallium was recovered in 2013. Globally, primary gallium gallium from imported primary gallium metal and new scrap. Imports of gallium, which supplied most of U

71

Accepted Manuscript Title: Isolation and characterization of Gallium resistant  

E-print Network

Accepted Manuscript Title: Isolation and characterization of Gallium resistant Pseudomonas of Gallium resistant Pseudomonas aeruginosa mutants, International Journal of Medical Microbiology (2013 Accepted M anuscript Isolation and characterization of Gallium resistant Pseudomonas aeruginosa mutants

Wood, Thomas K.

72

Measurement of arsenic and gallium content of gallium arsenide semiconductor waste streams by ICP-MS  

Microsoft Academic Search

The chemistry of semiconductor wafer processing liquid waste, contaminated by heavy metals, was investigated to determine arsenic content. Arsenic and gallium concentrations were determined for waste slurries collected from gallium arsenide (GaAs) wafer processing at three industrial sources and compared to slurries prepared under laboratory conditions. The arsenic and gallium content of waste slurries was analyzed using inductively coupled plasma

Keith W. Torrance; Helen E. Keenan; Andrew S. Hursthouse; David Stirling

2010-01-01

73

Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system  

E-print Network

Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system Kangkang, University of Michigan, Ann Arbor, MI 48109, U.S.A. ABSTRACT Ferromagnetic delta-phase manganese gallium to their potential for novel spintronics applications such as spin light-emitting diodes[1] . Delta phase manganese

74

Modelling of compound semiconductors: Analytical bondorder potential for gallium, nitrogen and gallium  

E-print Network

Modelling of compound semiconductors: Analytical bond­order potential for gallium, nitrogen and gallium nitride J Nordy, K Albez, P Erhartzand K Nordlundy y University of Helsinki, Accelerator.20.Ja,61.72.Bb 1. Introduction Gallium nitride is a semiconducting compound material of high

Nordlund, Kai

75

Epitaxial Deposition Of Germanium Doped With Gallium  

NASA Technical Reports Server (NTRS)

Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

Huffman, James E.

1994-01-01

76

Substrates for gallium nitride epitaxy  

Microsoft Academic Search

In this review, the structural, mechanical, thermal, and chemical properties of substrates used for gallium nitride (GaN) epitaxy are compiled, and the properties of GaN films deposited on these substrates are reviewed. Among semiconductors, GaN is unique; most of its applications uses thin GaN films deposited on foreign substrates (materials other than GaN); that is, heteroepitaxial thin films. As a

L. Liu; J. H. Edgar

2002-01-01

77

Determination of gallium by adsorptive stripping voltammetry.  

PubMed

A procedure for the determination of gallium by differential pulse adsorptive stripping voltammetry (DPADSV), using different complexing agents (ammonium pyrrolidine dithiocarbamate (APDC), pyrocatechol violet (PCV) and diethyldithiocarbamate (DDTC)), has been optimized. The selection of the experimental conditions was made using experimental design methodology. Under these conditions, the calibration was made and the detection limit was determined for each gallium-ligand complex. A robust regression method was applied which allowed the elimination of anomalous points. The detection limit, with alpha=beta=0.05, for gallium-APDC complex was 5.0x10(-8)moldm(-3), for gallium-PCV complex was 9.9x10(-9)moldm(-3), and the lowest detection limit (1.3x10(-9)moldm(-3)) was obtained with DDTC. For this reason, DDTC was selected for the determination of the gallium concentration in a certificate sample and in a spiked tap water sample. The linear dynamic range for gallium-APDC complex was from 5.0x10(-8) to 2.7x10(-7)moldm(-3), for gallium-PCV complex was from 5.0x10(-9) to 4.8x10(-7)moldm(-3), and for gallium-DDTC complex was from 1.0x10(-9) to 2.1x10(-7)moldm(-3). PMID:18969318

González, M Jesús Gómez; Renedo, Olga Dom? Nguez; Lomillo, M Asunción Alonso; Mart? Nez, M Julia Arcos

2004-02-27

78

Thermodynamic binding constants for gallium transferrin  

Microsoft Academic Search

Gallium-67 is widely used as an imaging agent for tumors and inflammatory abscesses. It is well stablished that Ga\\/sup 3 +\\/ travels through the circulatory system bound to the serum iron transport protein transferrin and that this protein binding is an essential step in tumor localization. However, there have been conflicting reports on the magnitude of the gallium-transferrin binding constants.

Wesley R. Harris; Vincent L. Pecoraro

1983-01-01

79

GALLIUM--1998 29.1 By Deborah A. Kramer  

E-print Network

GALLIUM--1998 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared by Carolyn F. Crews, statistical assistant. Gallium demand in the United States was satisfied by imports, primarily high-purity material from France and low- purity material from Russia. More than 95% of gallium

80

GALLIUM--2001 29.1 By Deborah A. Kramer  

E-print Network

GALLIUM--2001 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared in lower demand for gallium from the record-high levels that transpired in 2000. The largest factor influencing domestic gallium demand was the decline in the purchase of new cellular telephone products

81

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2010. One company in Utah  

E-print Network

58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2010. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

82

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2008. One company in Utah  

E-print Network

60 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2008. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

83

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2004. One company in Utah  

E-print Network

64 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2004. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

84

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2006. One company in Utah  

E-print Network

62 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2006. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

85

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1999. Two companies in  

E-print Network

66 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1999. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

86

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1998. Two companies in  

E-print Network

66 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1998. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

87

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1997. Two companies in  

E-print Network

62 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1997. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

88

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2012. One company in Utah  

E-print Network

58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2012. One company in Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most of U

89

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2000. Two companies in  

E-print Network

62 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2000. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

90

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1996. Two companies in  

E-print Network

62 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1996. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

91

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2005. One company in Utah  

E-print Network

66 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2005. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

92

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2003. One company in  

E-print Network

64 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2003. One company in Oklahoma recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

93

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2001. Two companies in  

E-print Network

64 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2001. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

94

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2002. Two companies in  

E-print Network

66 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2002. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

95

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2011. One company in Utah  

E-print Network

58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2011. One company in Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most of U

96

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2007. One company in Utah  

E-print Network

64 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2007. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

97

(Data in kilograms of gallium content, unless noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1995. Two companies in  

E-print Network

60 GALLIUM (Data in kilograms of gallium content, unless noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1995. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most of U

98

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2009. One company in Utah  

E-print Network

58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2009. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

99

Clinical Applications of Gallium-68  

PubMed Central

Gallium-68 is a positron-emitting radioisotope that is produced from a 68Ge/68Ga generator. As such it is conveniently used, decoupling radiopharmacies from the need for a cyclotron on site. Gallium-68-labeled peptides have been recognized as a new class of radiopharmaceuticals showing fast target localization and blood clearance. 68Ga-DOTATOC, 8Ga-DOTATATE, 68Ga-DOTANOC, are the most prominent radiopharmaceuticals currently in use for imaging and differentiating lesions of various somatostatin receptor subtypes, overexpressed in many neuroendocrine tumors. There has been a tremendous increase in the number of clinical studies with 68Ga over the past few years around the world, including within the United States. An estimated ~10,000 scans are being performed yearly in Europe at about 100 centers utilizing 68Ga-labeled somatostatin analogs within clinical trials. Two academic sites within the US have also begun to undertake human studies. This review will focus on the clinical experience of selected, well-established and recently applied 68Ga-labeled imaging agents used in nuclear medicine. PMID:23522791

Banerjee, Sangeeta Ray; Pomper, Martin G.

2013-01-01

100

Clinical applications of Gallium-68.  

PubMed

Gallium-68 is a positron-emitting radioisotope that is produced from a (68)Ge/(68)Ga generator. As such it is conveniently used, decoupling radiopharmacies from the need for a cyclotron on site. Gallium-68-labeled peptides have been recognized as a new class of radiopharmaceuticals showing fast target localization and blood clearance. (68)Ga-DOTATOC, (8)Ga-DOTATATE, (68)Ga-DOTANOC, are the most prominent radiopharmaceuticals currently in use for imaging and differentiating lesions of various somatostatin receptor subtypes, overexpressed in many neuroendocrine tumors. There has been a tremendous increase in the number of clinical studies with (68)Ga over the past few years around the world, including within the United States. An estimated ?10,000 scans are being performed yearly in Europe at about 100 centers utilizing (68)Ga-labeled somatostatin analogs within clinical trials. Two academic sites within the US have also begun to undertake human studies. This review will focus on the clinical experience of selected, well-established and recently applied (68)Ga-labeled imaging agents used in nuclear medicine. PMID:23522791

Banerjee, Sangeeta Ray; Pomper, Martin G

2013-06-01

101

In vitro bio-functionality of gallium nitride sensors for radiation biophysics  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Gallium nitride based sensors show promising characteristics to monitor cellular parameters. Black-Right-Pointing-Pointer Cell growth experiments reveal excellent biocompatibiltiy of the host GaN material. Black-Right-Pointing-Pointer We present a biofunctionality assay using ionizing radiation. Black-Right-Pointing-Pointer DNA repair is utilized to evaluate material induced alterations in the cellular behavior. Black-Right-Pointing-Pointer GaN shows no bio-functional influence on the cellular environment. -- Abstract: There is an increasing interest in the integration of hybrid bio-semiconductor systems for the non-invasive evaluation of physiological parameters. High quality gallium nitride and its alloys show promising characteristics to monitor cellular parameters. Nevertheless, such applications not only request appropriate sensing capabilities but also the biocompatibility and especially the biofunctionality of materials. Here we show extensive biocompatibility studies of gallium nitride and, for the first time, a biofunctionality assay using ionizing radiation. Analytical sensor devices are used in medical settings, as well as for cell- and tissue engineering. Within these fields, semiconductor devices have increasingly been applied for online biosensing on a cellular and tissue level. Integration of advanced materials such as gallium nitride into these systems has the potential to increase the range of applicability for a multitude of test devices and greatly enhance sensitivity and functionality. However, for such applications it is necessary to optimize cell-surface interactions and to verify the biocompatibility of the semiconductor. In this work, we present studies of mouse fibroblast cell activity grown on gallium nitride surfaces after applying external noxa. Cell-semiconductor hybrids were irradiated with X-rays at air kerma doses up to 250 mGy and the DNA repair dynamics, cell proliferation, and cell growth dynamics of adherent cells were compared to control samples. The impact of ionizing radiation on DNA, along with the associated cellular repair mechanisms, is well characterized and serves as a reference tool for evaluation of substrate effects. The results indicate that gallium nitride does not require specific surface treatments to ensure biocompatibility and suggest that cell signaling is not affected by micro-environmental alterations arising from gallium nitride-cell interactions. The observation that gallium nitride provides no bio-functional influence on the cellular environment confirms that this material is well suited for future biosensing applications without the need for additional chemical surface modification.

Hofstetter, Markus [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Howgate, John [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Schmid, Martin [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Schoell, Sebastian; Sachsenhauser, Matthias [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Adiguezel, Denis [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Stutzmann, Martin; Sharp, Ian D. [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Thalhammer, Stefan, E-mail: stefan.thalhammer@helmholtz-muenchen.de [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)

2012-07-27

102

The Soviet American Gallium Experiment (SAGE)  

SciTech Connect

A radiochemical experiment using the reaction v/sub e/ = /sup 71/Ga + e/sup e/ to determine the integral flux of low-energy neutrinos from the sun is currently under preparation at the Baksan Neutrino Observatory in the USSR. Measurements are scheduled to commence by late 1988 using /approximately/30 tonnes of metallic gallium. With this amount of gallium it should be possible to obtain a fractional statistical accuracy of 12 to 15% after one year (assuming the standard solar model neutrino flux). While initial measurements are in progress, installation of the remaining 30 tonnes of gallium will proceed in order to perform the full 60 tonne experiment.

Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.P.; Avdeyev, A.V.; Belousko, Yu.I.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gayevsky, V.I.; Gavrin, V.N.; Grigorjev, A.M.; Kalikhov, A.V.; Kireyev, S.M.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentsevah, S.A.; Mirnov, I.N.; Ejikbosverpdze, Sh.M.; Ostrinsky, A.V.; Petukhov, V.V.; Pikhulya, O.E.; Pshukov, A.M.; Revzin, N.Ye.; Shikhin, A.A.; Shilo, Yu.I.; Slyusareva, Ye.D.; Strepanyuk, M.V.; Tikhonov, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Yants, V.E.; Zakhorov, Yu.I.; Zatsepin, G.T.; Cleveland, B.C.; Bowles, T.J.; Elliott, S.R.; O'Brien, H.A.; Wark, D.L.; Wilkerson, J.F.; Cherry, M.L.; Kouzes, R.T.

1988-01-01

103

The surface tension of liquid gallium  

NASA Technical Reports Server (NTRS)

The surface tension of liquid gallium has been measured using the sessile drop technique in an Auger spectrometer. The experimental method is described. The surface tension in mJ/sq m is found to decrease linearly with increasing temperature and may be represented as 708-0.66(T-29.8), where T is the temperature in centigrade. This result is of interest because gallium has been suggested as a model fluid for Marangoni flow experiments. In addition, the surface tension is of technological significance in the processing of compound semiconductors involving gallium.

Hardy, S. C.

1985-01-01

104

The solubility of hydrogen and deuterium in alloyed, unalloyed and impure plutonium metal  

SciTech Connect

Pressure-Composition-Temperature (PCT) data are presented for the plutonium-hydrogen (Pu-H) and plutonium-deuterium (Pu-D) systems in the solubility region up to terminal solubility (precipitation of PuH{sub 2}). The heats of solution for PuH{sub s} and PuD{sub s} are determined from PCT data in the ranges 350-625 C for gallium alloyed Pu and 400-575 C for unalloyed Pu. The solubility of high purity plutonium alloyed with 2 at.% gallium is compared to high purity unalloyed plutonium. Significant differences are found in hydrogen solubility for unalloyed Pu versus gallium alloyed Pu. Differences in hydrogen solubility due to an apparent phase change are observable in the alloyed and unalloyed solubilities. The effect of iron impurities on Pu-Ga alloyed Pu is shown via hydrogen solubility data as preventing complete homogenization.

Richmond, Scott [Los Alamos National Laboratory; Bridgewater, Jon S [Los Alamos National Laboratory; Ward, John W [Los Alamos National Laboratory; Allen, Thomas A [Los Alamos National Laboratory

2009-01-01

105

Radiochemical separation of gallium by amalgam exchange  

USGS Publications Warehouse

An amalgam-exchange separation of radioactive gallium from a number of interfering radioisotopes has been developed. A dilute (ca. 0.3%) gallium amalgam is agitated with a slightly acidic solution of 72Ga3+ containing concentrations of sodium thiocyanate and either perchlorate or chloride. The amalgam is then removed and the radioactive gallium stripped by agitation with dilute nitric acid. The combined exchange yield of the perchlorate-thiocyanate system is 90??4% and that of the chloride-thiocyanate system is 75??4%. Decontamination yields of most of the 11 interfering isotopes studied were less than 0.02%. The technique is applicable for use with activation analysis for the determination of trace amounts of gallium. ?? 1969.

Ruch, R.R.

1969-01-01

106

Thermal Conductivity of Indium-Graphene and Indium-Gallium-Graphene Composites  

NASA Astrophysics Data System (ADS)

Samples of graphene composites with a matrix of indium or indium-gallium alloy were prepared in the form of foils using exfoliated graphene dispersions. The thermal conductivity of the composite samples with different thicknesses was determined using the three-omega method. Indium-graphene composite samples with a thickness of 430 ?m exhibited a twofold increase in thermal conductivity, whereas indium-gallium-graphene composite samples with a thickness of 330 ?m exhibited a threefold improvement in thermal conductivity over that of the matrix at 300 K. The effective medium approximation (EMA) was used to model the thermal conductivity of the composite samples. The graphene platelet size distribution was used to determine the average thermal conductivity of graphene in the composite samples. The interfacial thermal conductance between graphene and indium or indium-gallium alloy determined from EMA was not the limiting factor in the improvement of the thermal conductivity of the composite samples, although the increase in thermal conductivity was found to be slightly lower than predicted theoretically using acoustic and diffuse mismatch models. The smaller size of the graphene platelets obtained by exfoliation prior to dispersion in the matrix appears to be the limiting factor.

Jagannadham, K.

2011-01-01

107

Generator for gallium-68 and compositions obtained therefrom  

DOEpatents

A generator for obtaining radioactive gallium-68 from germanium-68 bound in a resin containing unsubstituted phenolic hydroxyl groups. The germanium-68 is loaded into the resin from an aqueous solution of the germanium-68. A physiologically acceptable solution of gallium-68 having an activity of 0.1 to 50 millicuries per milliliter of gallium-68 solution is obtained. The solution is obtained from the bound germanium-68 which forms gallium-68 in situ by eluting the column with a hydrochloric acid solution to form an acidic solution of gallium-68. The acidic solution of gallium-68 can be neutralized.

Neirinckx, Rudi D. (Medfield, MA); Davis, Michael A. (Westwood, MA)

1981-01-01

108

Development of gallium arsenide solar cells  

NASA Technical Reports Server (NTRS)

The potential of ion implantation as a means of developing gallium arsenide solar cells with high efficiency performance was investigated. Computer calculations on gallium arsenide cell characteristics are presented to show the effects of surface recombination, junction space-charge recombination, and built-in fields produced by nonuniform doping of the surface region. The fabrication technology is summarized. Electrical and optical measurements on samples of solar cells are included.

1973-01-01

109

High-dose gallium imaging in lymphoma  

Microsoft Academic Search

The role of gallium-67 imaging in the management of patients with lymphoma, traditionally assessed using low tracer doses and the rectilinear scanner, was assessed when using larger doses (7 to 10 mCi) and a triple-peak Anger camera. Gallium scan results in 51 patients with non-Hodgkin's lymphoma and 21 patients with Hodgkin's disease were compared with simultaneous radiologic, clinical, and histopathologic

Kenneth C. Anderson; Robert C. F. Leonard; George P. Canellos; Arthur T. Skarin; William D. Kaplan

1983-01-01

110

Use of gallium-67 in pulmonary disorders  

Microsoft Academic Search

Imaging of the chest cage with gallium-67 (⁶⁷Ga) citrate is relatively easier to perform and interpret than imaging of the abdomen, because normally pulmonary concentration is low after 48 hr and physiologic accumulation in bones and breast can be recognized by its distribution. Modern scintillation detectors, particularly large field cameras with multiple pulse-height analyzers, give substantially better gallium images than

J. K. Siemsen; S. F. Grebe; A. D. Waxman

1978-01-01

111

Ultrasonic Doppler velocimetry in liquid gallium  

Microsoft Academic Search

For the first time, flow velocity is measured in a vortex of liquid gallium, using the pulsed Doppler shift ultrasonic method.\\u000a At the top of a copper cylinder filled with liquid gallium, we spin a disk and create a turbulent vortex with a dominant nearly\\u000a axisymmetric velocity field with little variation in the axial direction. The velocity profiles are shown

Daniel Brito; Henri-Claude Nataf; Philippe Cardin; Julien Aubert; Jean-Paul Masson

2001-01-01

112

Chemical and electronic characterization of copper indium gallium diselenide thin film solar cells and correlation of these characteristics to solar cell operation  

Microsoft Academic Search

This dissertation embodies solid state physics research to understand the basic physical mechanisms underlying the movement of charge inside solar cells, in particular, the high efficiency copper indium gallium diselenide (CIGS) solar cell. The fundamental physics of the operation of these complex polycrystalline alloys remains incompletely understood. CIGS based solar cells have obtained conversion efficiencies of nearly 20%. Solar cells

Michael Justin Hetzer

2009-01-01

113

JOURNAL DE PHYSIQUE Colloque C4, supplkment au no 5, Tome 35, Mai 1974,page C4-313 LORENZ NUMBER AND THERMAL CONDUCTIVITY OF LIQUID GALLIUM,  

E-print Network

AND THERMAL CONDUCTIVITY OF LIQUID GALLIUM, MERCURY AND MERCURY-INDIUM ALLOYS G. BUSCH, H.-J. GUNTHERODT, W (derived from separate measurements of the thermal and electrical conductivity) of the liquid metals value for the Lorenz number. The thermal conductivity has been calculated from the Lorenz number

Paris-Sud XI, Université de

114

Window structure for passivating solar cells based on gallium arsenide  

SciTech Connect

Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

Barnett, A. M.

1985-10-01

115

Window structure for passivating solar cells based on gallium arsenide  

NASA Technical Reports Server (NTRS)

Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

Barnett, Allen M. (Inventor)

1985-01-01

116

Au-free Ohmic Contacts to Gallium Nitride and Graphene  

E-print Network

This work deals with Au-free contact metallization schemes for gallium nitride (GaN) and graphene semiconductors. Graphene and gallium nitride are promising materials that can potentially be integrated together in the near future for high frequency...

Ravikirthi, Pradhyumna

2014-08-10

117

Directing substrate morphology via self-assembly: ligand-mediated scission of gallium-indium microspheres to the nanoscale.  

PubMed

We have developed a facile method for the construction of liquid-phase eutectic gallium-indium (EGaIn) alloy nanoparticles. Particle formation is directed by molecular self-assembly and assisted by sonication. As the bulk liquid alloy is ultrasonically dispersed, fast thiolate self-assembly at the EGaIn interface protects the material against oxidation. The choice of self-assembled monolayer ligand directs the ultimate size reduction in the material; strongly interacting molecules induce surface strain and assist particle cleavage to the nanoscale. Transmission electron microscopy images and diffraction analyses reveal that the nanoscale particles are in an amorphous or liquid phase, with no observed faceting. The particles exhibit strong absorption in the ultraviolet (?200 nm), consistent with the gallium surface plasmon resonance, but dependent on the nature of the particle ligand shell. PMID:22023557

Hohman, J Nathan; Kim, Moonhee; Wadsworth, Garrett A; Bednar, Heidi R; Jiang, Jun; LeThai, Mya A; Weiss, Paul S

2011-12-14

118

INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation  

E-print Network

1 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation Submitted to the Graduate;2 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS Abstract by Sajid Kabeer In0.53Ga0.47As tunnel-type dopant, exhibited a backward diode behavior. #12;4 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS

119

Standard Reference Material 1751: Gallium Melting-Point Standard  

E-print Network

Standard Reference Material 1751: Gallium Melting-Point Standard Gregory F. Strouse NIST Special Publication 260-157 #12;#12;NIST Special Publication 260-157 XXXX Standard Reference Material 1751: Gallium Reference Material 1751: Gallium Melting-Point Standard Gregory F. Strouse National Institute of Standards

120

An Asynchronous Microprocessor in Gallium Jose A. Tierno  

E-print Network

An Asynchronous Microprocessor in Gallium Arsenide Jose A. Tierno Alain J. Martin Dralen Borkovic Asynchronous Microprocessor in Gallium Arsenide Jose A. Tierno Alain J. Martin Drazen Borkovic Tak Kwan Lee Abstract In this paper, several techniques for designing asynchronous circuits in Gallium Arsenide

Martin, Alain

121

Photoelectron energy distribution and spin polarization from activated gallium arsenide  

E-print Network

L-1027 Photoelectron energy distribution and spin polarization from activated gallium arsenide H ont été effectuées sur des photoélectrons émis par un cristal d'arséniure de gallium activé. Les.90 1. Introduction. It has been shown [1-4] that a p-type gallium arsenide crystal activated

Paris-Sud XI, Université de

122

The wetting of alumina by copper alloyed with titanium and other elements  

Microsoft Academic Search

The wettability of alumina by ternary alloys of copper, titanium and aluminium, gallium gold, indium, nickel or silver has been investigated using sessile drop tests conducted in vacuum at 1050–1250° C. Substantial additions of titanium are known to induce copper to wet alumina due to the formation of a titanium rich reaction product at the alloy\\/ ceramic interface, but the

M. G. Nicholas; T. M. Valentine; M. J. Waite

1980-01-01

123

Spontaneous formation of quantum height manganese gallium islands and atomic chains on N-polar gallium nitride(0001)  

E-print Network

Spontaneous formation of quantum height manganese gallium islands and atomic chains on N-polar gallium nitride(0001) Abhijit Chinchore, Kangkang Wang,a) Meng Shi, Yinghao Liu,b) and Arthur R. Smithc) Deposition of manganese onto the gallium-rich, nitrogen-polar GaN(0001) surface results in the formation

124

New SMU Gallium Fixed-Point Cells  

NASA Astrophysics Data System (ADS)

In the framework of the European research project EURAMET 732, the Slovak Institute of Metrology (SMU) built three primary gallium fixed-point cells of different designs. The cells are designed for the calibration of the long-stem SPRT. In regard to the procedure commonly used at SMU when realizing the gallium point, the cells are designed for use in a stirred liquid bath. This article provides information about the cell designs, materials used, method of filling, and results of the performed experiments. The experiments were focused on the study of the cells' metrological characteristics, some effects that could influence the melting-point temperature and the effect of the melted metal fraction on the immersion profile. New cells were compared with the SMU reference gallium cell.

Ranostaj, Juraj; ?uriš, Stanislav; Knorová, Renáta; Kaskötö, Mariana; Vysko?ilová, Irena

2011-08-01

125

/sup 67/Gallium lung scans in progressive systemic sclerosis  

SciTech Connect

/sup 67/Gallium lung scans were performed in 19 patients with progressive systemic sclerosis (scleroderma). Results were expressed quantitatively as the /sup 67/Gallium Uptake Index. The mean total pulmonary /sup 67/Gallium Uptake Index in patients was significantly higher than that in controls (41 versus 25), and 4 patients (21%) fell outside the normal range. There were no clinical or laboratory variables that correlated with the /sup 56/Gallium uptake. Increased pulmonary /sup 67/Gallium uptake in scleroderma may prove useful as an index of pulmonary disease activity.

Baron, M.; Feiglin, D.; Hyland, R.; Urowitz, M.B.; Shiff, B.

1983-08-01

126

Radiation damage of gallium arsenide production cells  

NASA Technical Reports Server (NTRS)

High efficiency liquid phase epitaxy (LPE) gallium arsenide cells were irradiated with 1 Mev electrons up to fluences of 1 times 10 to the 16th power cm-2. Measurements of spectral response and dark and illuminated I-V data were made at each fluence and then, using computer codes, the experimental data was fitted to gallium arsenide cell models. In this way it was possible to determine the extent of the damage, and hence damage coefficients in both the emitter and base of the cell.

Mardesich, N.; Joslin, D.; Garlick, J.; Lillington, D.; Gillanders, M.; Cavicchi, B.; Scott-Monck, J.; Kachare, R.; Anspaugh, B.

1987-01-01

127

Atomistic modeling of thermodynamic properties of Pu-Ga alloys based on the Invar mechanism  

NASA Astrophysics Data System (ADS)

We present an atomistic model that accounts for a range of anomalous thermodynamic properties of the fcc ? phase of Pu-Ga alloys in terms of the Invar mechanism. Two modified embedded atom method potentials are employed to represent competing electronic states in ?-Pu, each of which has an individual configuration dependence as well as distinct interactions with gallium. Using classical Monte Carlo simulations, we compute the temperature dependence of various thermodynamic properties for different dilute gallium concentrations. The model reproduces the observed effects of excessive volume reduction along with a rapid shift in thermal expansion from negative to positive values with increasing gallium concentration. It also predicts progressive stiffening upon dilute-gallium alloying, while the calculated thermal softening is nearly independent of the gallium concentration in agreement with resonant ultrasound spectroscopy measurements in the literature. Analysis of the local structure predicted by the model indicates that the distribution of the gallium atoms is not completely random in the ? phase due to the presence of short-range order associated with the Invar mechanism. This effect is consistent with the nanoscale heterogeneity in local gallium concentration which is observed in recent extended x-ray absorption fine structure spectroscopy experiments. Implications of the Invar effect for phase stability and physical interpretations of the two states are also discussed.

Lee, Tongsik; Taylor, Christopher D.; Lawson, A. C.; Conradson, Steven D.; Chen, Shao Ping; Caro, A.; Valone, Steven M.; Baskes, Michael I.

2014-05-01

128

Four Terminal Gallium Nitride MOSFETs  

NASA Astrophysics Data System (ADS)

All reported gallium nitride (GaN) transistors to date have been three-terminal devices with source, drain, and gate electrodes. In the case of GaN MOSFETs, this leaves the bulk of the device at a floating potential which can impact device threshold voltage. In more traditional silicon-based MOSFET fabrication a bulk contact can be made on the back side of the silicon wafer. For GaN grown on sapphire substrates, however, this is not possible and an alternate, front-side bulk contact must be investigated. GaN is a III-V, wide band gap semiconductor that as promising material parameters for use in high frequency and high power applications. Possible applications are in the 1 to 10 GHz frequency band and power inverters for next generation grid solid state transformers and inverters. GaN has seen significant academic and commercial research for use in Heterojunction Field Effect Transistors (HFETs). These devices however are depletion-mode, meaning the device is considered "on" at zero gate bias. A MOSFET structure allows for enhancement mode operation, which is normally off. This mode is preferrable in high power applications as the device has lower off-state power consumption and is easier to implement in circuits. Proper surface passivation of seminconductor surface interface states is an important processing step for any device. Preliminary research on surface treatments using GaN wet etches and depletion-mode GaN devices utilizing this process are discussed. Devices pretreated with potassium pursulfate prior to gate dielectric deposition show significant device improvements. This process can be applied to any current GaN FET. Enhancement-mode GaN MOSFETs were fabricated on magnesium doped p-type Wurtzite gallium nitride grown by Metal Organic Chemical Vapor Deposition (MOCVD) on c-plane sapphire substrates. Devices utilized ion implant source and drain which was activated under NH3 overpressure in MOCVD. Also, devices were fabricated with a SiO2 gate dielectric and metal gate. Preliminary devices exhibited high GaN-oxide interface state density, Dit, on the order of 1013 cm-2· eV-1. Additional experiments and device fabrication was focused on improving device performance through optimization of the ion implantation activation anneal as well as incorporation of a bulk p-type ohmic contact and migration to a thicker, lower defect density, HVPE-grown template substrate. The first reported MOSFET on HVPE grown GaN substrates (templates) is reported with peak measured drain current of 1.05 mA/mm and a normalized transconductance of 57 muS/mm. Fabricated devices exhibited large (greater than 1 muA) source-to-drain junction leakage which is attributed to low activated doping density in the MOCVD-grown p-type bulk. MOSFETs fabricated on template substrates show more than twice the measured drain current as similar devices fabricated on traditional MOCVD GaN on sapphire substrates for the same bias conditions. Also, template MOSFETs have decreased gate leakage which allowed for a much greater range of operation. This performance increase is attributed to a more than doubled effective channel mobility on template GaN MOSFETs due to decreased crystal defect scattering when compared to a MOCVD-grown GaN-on-sapphire MOSFET. Fabricated MOSFETs also exhibit decreased interface state density with lower bound of 2.2x1011 cm-2·eV-1 when compared to prelimary MOSFETs. This decrease is associated with the use of a sacrificial oxide cap during source/drain activation. Suggested work for continued research is also presented which includes experiments to improve source/drain ion implantation profile, utilization of selective area growth for the active area, improved n- and p-type ohmic contact resistance and investigation of alternate oxides.

Veety, Matthew Thomas

129

Emerging gallium nitride based devices  

Microsoft Academic Search

Wide bandgap GaN has long been sought for its applications to blue and UV emitters and high temperature\\/high power electronic devices. Recent introduction of commercial blue and blue-green LED's have led to a plethora of activity in all three continents into the heterostructures based on GaN and its alloys with AlN and InN. In this review, the status and future

S. N. Mohammad; ARNEL A. SALVADOR; HADIS MORKOC

1995-01-01

130

The Influence of Lewis Acid/Base Chemistry on the Removal of Gallium by Volatility from Weapons-Grade Plutonium Dissolved in Molten Chlorides  

SciTech Connect

It has been proposed that GaCl{sub 3} can be removed by direct volatilization from a Pu-Ga alloy that is dissolved in a molten chloride salt. Although pure GaCl{sub 3} is quite volatile (boiling point: 201 deg. C), the behavior of GaCl{sub 3} dissolved in chloride salts is quite different because of solution effects and is critically dependent upon the composition of the solvent salt (i.e., its Lewis acid/base character). In this technical note, the behavior of gallium in prototypical Lewis acid and Lewis base salts is contrasted. It is found that gallium volatility is suppressed in basic melts and promoted in acidic melts. These results have an important influence on the potential for simple gallium removal in molten salt systems.

Williams, David F.; Cul, Guillermo D. del [Oak Ridge National Laboratory (United States); Toth, Louis M. [Electrochemical Systems (United States); Collins, Emory D. [Oak Ridge National Laboratory (United States)

2001-12-15

131

Thermodynamic binding constants for gallium transferrin  

SciTech Connect

Gallium-67 is widely used as an imaging agent for tumors and inflammatory abscesses. It is well stablished that Ga/sup 3 +/ travels through the circulatory system bound to the serum iron transport protein transferrin and that this protein binding is an essential step in tumor localization. However, there have been conflicting reports on the magnitude of the gallium-transferrin binding constants. Therefore, thermodynamic binding constants for gallium complexation at the two specific metal binding sites of human serum transferrin at pH 7.4 and 5 mM NaHCO/sub 3/ have been determined by UV difference spectroscopy. The conditional constants calculated for 27 mM NaHCO/sub 3/ are log K/sub 1/* = 20.3 and log K/sub 2/* = 19.3. These results are discussed in relation to the thermodynamics of transferrin binding of Fe/sup 3 +/ and to previous reports on gallium binding. The strength of transferrin complexation is also compared to that of a series of low molecular weight ligands by using calculated pM values (pM = -log (Ga(H/sub 2/O)/sub 6/)) to express the effective binding strength at pH 7.4.

Harris, W.R.; Pecoraro, V.L.

1983-01-18

132

Gallium Electromagnetic (GEM) Thruster Performance Measurements  

NASA Technical Reports Server (NTRS)

Discharge current, terminal voltage, and mass bit measurements are performed on a coaxial gallium electromagnetic thruster at discharge currents in the range of 7-23 kA. It is found that the mass bit varies quadratically with the discharge current which yields a constant exhaust velocity of 20 km/s. Increasing the electrode radius ratio of the thruster from to 2.6 to 3.4 increases the thruster efficiency from 21% to 30%. When operating with a central gallium anode, macroparticles are ejected at all energy levels tested. A central gallium cathode ejects macroparticles when the current density exceeds 3.7 10(exp 8) A/square m . A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma. The spectra show that neutral, singly, and doubly ionized gallium species are present in the discharge, as well as annular electrode species at higher energy levels. Axial Langmuir triple probe measurements yield electron temperatures in the range of 0.8-3.8 eV and electron densities in the range of 8 x 10(exp )20 to 1.6 x 10(exp 21) m(exp -3) . Triple probe measurements suggest an exhaust plume with a divergence angle of 9 , and a completely doubly ionized plasma at the ablating thruster cathode.

Thomas, Robert E.; Burton, Rodney L.; Polzin, K. A.

2009-01-01

133

Pulmonary gallium-67 uptake in amiodarone pneumonitis  

SciTech Connect

Three patients are presented suffering from interstitial pneumonitis caused by amiodarone. Pulmonary Ga-67 uptake occurred in all three. There appeared to be a discrepancy between the scintigraphic and radiographic findings in two patients. Gallium-67 lung scintigraphy may offer an early, sensitive indicator for amiodarone pneumonitis.

van Rooij, W.J.; van der Meer, S.C.; van Royen, E.A.; van Zandwijk, N.; Darmanata, J.I.

1984-02-01

134

Pulmonary gallium-67 uptake in amiodarone pneumonitis  

Microsoft Academic Search

Three patients are presented suffering from interstitial pneumonitis caused by amiodarone. Pulmonary Ga-67 uptake occurred in all three. There appeared to be a discrepancy between the scintigraphic and radiographic findings in two patients. Gallium-67 lung scintigraphy may offer an early, sensitive indicator for amiodarone pneumonitis.

W. J. van Rooij; S. C. van der Meer; E. A. van Royen; N. van Zandwijk; J. I. Darmanata

1984-01-01

135

Gallium-positive Lyme disease myocarditis  

SciTech Connect

In the course of a work-up for fever of unknown origin associated with intermittent arrhythmias, a gallium scan was performed which revealed diffuse myocardial uptake. The diagnosis of Lyme disease myocarditis subsequently was confirmed by serologic titers. One month following recovery from the acute illness, the abnormal myocardial uptake completely resolved.

Alpert, L.I.; Welch, P.; Fisher, N.

1985-09-01

136

Beryllium diffusion properties in dilute nitride alloys of gallium arsenide  

NASA Astrophysics Data System (ADS)

III-V dilute nitrogen materials (GaAsN and GaInNAs) are excellent candidates for long wavelength optoelectronic applications, including Lasers, HBTs and solar cells. The research of diffusion phenomenon and mechanism in these materials is an important topic for both research and manufacturing. The objective of this study was to investigate and discuss Be diffusion behavior and its mechanism in lightly and dilute N doped GaAs by chemical beam epitaxy (CBE) growth. The diffusivity and activation energy with nitrogen composition of 0.01% and 2% incorporation by radio frequency (RF) nitrogen plasma assisted chemical beam epitaxial growth of GaAs are reported here for the first time. The SIMS and ECV profiles of as-grown and annealed samples are investigated to provide a theoretical fit to compare the feature of diffusion behavior on both samples of different N doping content. Furthermore, we discuss interaction of charged point defects and the effect of N and H doping on Be diffusion. There is also an attempt to explain the experimental results with a diffusion mechanism. It may have a profound impact on the design and fabrication process of dilute nitride based devices.

Zhu, Wenkai

137

Gallium 67 scintigraphy in glomerular disease  

SciTech Connect

To evaluate the diagnostic usefulness of gallium 67 scintigraphy in glomerular disease, 45 patients with various glomerulopathies, excluding lupus nephritis and renal vasculitis, were studied. Persistent renal visualization 48 hours after the gallium injection, a positive scintigram, was graded as + (less than), ++ (equal to), and +++ (greater than) the hepatic uptake. Positive scintigrams were seen in ten of 16 cases of focal segmental glomerulosclerosis, six of 11 cases of proliferative glomerulonephritis, and one case of minimal change, and one of two cases of membranous nephropathy; also in three of six cases of sickle glomerulopathy, two cases of diabetic neuropathy, one of two cases of amyloidosis, and one case of mild chronic allograft rejection. The 25 patients with positive scans were younger than the 20 with negative scans (31 +/- 12 v 42 +/- 17 years; P less than 0.01), and exhibited greater proteinuria (8.19 +/- 7.96 v 2.9 +/- 2.3 S/d; P less than 0.01) and lower serum creatinine values (2 +/- 2 v 4.1 +/- 2.8 mg/dL; P less than 0.01). The amount of proteinuria correlated directly with the intensity grade of the gallium image (P less than 0.02), but there was no correlation between the biopsy diagnosis and the outcome of the gallium scan. It was concluded that gallium scintigraphy is not useful in the differential diagnosis of the glomerular diseases under discussion. Younger patients with good renal function and heavy proteinuria are likely to have a positive renal scintigram regardless of the underlying glomerulopathy.

Bakir, A.A.; Lopez-Majano, V.; Levy, P.S.; Rhee, H.L.; Dunea, G.

1988-12-01

138

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2010 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2010-07-01

139

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2014 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2014-07-01

140

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2012 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2012-07-01

141

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2013 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2013-07-01

142

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2011 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2011-07-01

143

Indium gallium nitride/gallium nitride quantum wells grown on polar and nonpolar gallium nitride substrates  

NASA Astrophysics Data System (ADS)

Nonpolar (m-plane or a-plane) gallium nitride (GaN) is predicted to be a potential substrate material to improve luminous efficiencies of nitride-based quantum wells (QWs). Numerical calculations indicated that the spontaneous emission rate in a single In0.15Ga0.85N/GaN QW could be improved by ˜2.2 times if the polarization-induced internal field was avoided by epitaxial deposition on nonpolar substrates. A challenge for nonpolar GaN is the limited size (less than 10x10 mm2) of substrates, which was addressed by expansion during the regrowth by Hydride Vapor Phase Epitaxy (HVPE). Subsurface damage in GaN substrates were reduced by annealing with NH3 and N2 at 950°C for 60 minutes. It was additionally found that the variation of m-plane QWs' emission properties was significantly increased when the substrate miscut toward a-axis was increased from 0° to 0.1°. InGaN/GaN QWs were grown by Metalorganic Chemical Vapor Deposition (MOCVD) on c-plane and m-plane GaN substrates. The QWs were studied by cathodoluminescence spectroscopy with different incident electron beam probe currents (0.1 nA ˜ 1000 nA). Lower emission intensities and longer peak wavelengths from c-plane QWs were attributed to the Quantum-confined Stark Effect (QCSE). The emission intensity ratios of m-plane QWs to c-plane QWs decreased from 3.04 at 1 nA to 1.53 at 1000 nA. This was identified as the stronger screening effects of QCSE at higher current densities in c-plane QWs. To further investigate these effects in a fabricated structure, biased photoluminescence measurements were performed on m-plane InGaN/GaN QWs. The purpose was to detect the possible internal fields induced by the dot-like structure in the InGaN layer through the response of these internal fields under externally applied fields. No energy shifts of the QWs were observed, which was attributed to strong surface leakage currents.

Lai, Kun-Yu

144

Inflammatory pseudotumor: A gallium-avid mobile mesenteric mass  

SciTech Connect

An 8-yr-old boy with a 1-mo history of culture-negative fever and anemia underwent gallium, ultrasound, and computed tomography studies as part of the evaluation of a fever of unknown origin. These studies revealed a mobile gallium-avid solid abdominal mass subsequently proven to be an inflammatory pseudotumor of the mesentery, a rare benign mass. This report documents the gallium-avid nature of this rare lesion and discusses associated characteristic clinical, pathologic, and radiographic features.

Auringer, S.T.; Scott, M.D.; Sumner, T.E. (Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC (USA))

1991-08-01

145

Surface photovoltage spectroscopy applied to gallium arsenide surfaces  

NASA Technical Reports Server (NTRS)

The experimental and theoretical basis for surface photovoltage spectroscopy is outlined. Results of this technique applied to gallium arsenide surfaces, are reviewed and discussed. The results suggest that in gallium arsenide the surface voltage may be due to deep bulk impurity acceptor states that are pinned at the Fermi level at the surface. Establishment of the validity of this model will indicate the direction to proceed to increase the efficiency of gallium arsenide solar cells.

Bynik, C. E.

1975-01-01

146

Far-infrared lattice absorption in gallium phosphide B. Pdr (*)  

E-print Network

737 Far-infrared lattice absorption in gallium phosphide B. Pödör (*) Research Laboratory de phosphure de gallium a été mesurée en utilisant un spectromètre à transformée de Fourier à 300 et-infrared lattice absorption in gallium phosphide was measured using a Fourier-transform spectrometer at 300 and 100

Paris-Sud XI, Université de

147

Photonuclear Reaction Cross Sections for Gallium Isotopes  

E-print Network

The photon induced reactions which are named as photonuclear reactions have a great importance in many field of nuclear, radiation physics and related fields. Since we have planned to perform photonuclear reaction on gallium target with bremmstrahlung photons from clinical linear accelerator in the future, the cross-sections of neutron (photo-neutron ({\\gamma},xn)) and proton (photo-proton ({\\gamma},xn)) productions after photon activation have been calculated by using TALYS 1.2 computer code in this study. The target nucleus has been considered gallium which has two stable isotopes, 69Ga and 71Ga. According to the results, we have seen that the calculations are in harmony in the limited literature values. Furthermore, the pre-equilibrium and compound process contributions to the total cross-section have been investigated.

Serkan Akkoyun; Tuncay Bayram

2014-09-08

148

Gallium arsenide photo-field emission  

Microsoft Academic Search

The development of monochromatic ultrafast electron sources with high brightness and high coherence is increasingly important in both time-resolved and energy-resolved electron microscopy. This work details the fabrication of intrinsic Gallium-Arsenide photo-field emitters and their evaluation as potential source candidates. The emitters were prepared via chemical etching and vacuum heat cleansing of cleaved wafer shards that had been mounted in

Theodore Vecchione

2009-01-01

149

The Baksan gallium solar neutrino experiment  

SciTech Connect

A radiochemical /sup 71/Ga-/sup 71/Ge experiment to determine the integral flux of neutrinos from the sun has been constructed at the Baksan Neutrino Observatory in the USSR. Measurements have begun with 30 tonnes of gallium. The experiment is being expanded with the addition of another 30 tonnes. The motivation, experimental procedures, and present status of this experiment are presented. 43 refs., 1 fig., 1 tab.

Gavrin, V.N.; Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.L.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gayevsky, V.I.; Girin, S.V.

1989-01-01

150

Gallium arsenide - Solar panel assembly technology  

Microsoft Academic Search

Gallium arsenide (GaAs) solar cell devices are maturing at 18 percent AM0 efficiencies for liquid phase epitaxy (LPE) technology, and efforts must be intensified placing necessary focus on the development of panel assembly techniques, and ultimately panel manufacturing methods capable of maintaining these high efficiencies for on-panel operation. Key problems and solutions are described which were experienced during the assembly

D. Zemmrich; N. Mardesich; B. Macfarlane; R. Loo

1984-01-01

151

Repurposing of gallium-based drugs for antibacterial therapy.  

PubMed

While the occurrence and spread of antibiotic resistance in bacterial pathogens is vanishing current anti-infective therapies, the antibiotic discovery pipeline is drying up. In the last years, the repurposing of existing drugs for new clinical applications has become a major research area in drug discovery, also in the field of anti-infectives. This review discusses the potential of repurposing previously approved gallium formulations in antibacterial chemotherapy. Gallium has no proven function in biological systems, but it can act as an iron-mimetic in both prokaryotic and eukaryotic cells. The activity of gallium mostly relies on its ability to replace iron in redox enzymes, thus impairing their function and ultimately hampering cell growth. Cancer cells and bacteria are preferential gallium targets due to their active metabolism and fast growth. The wealth of knowledge on the pharmacological properties of gallium has opened the door to the repurposing of gallium-based drugs for the treatment of infections sustained by antibiotic-resistant bacterial pathogens, such as Acinetobacter baumannii or Pseudomonas aeruginosa, and for suppression of Mycobacterium tuberculosis growth. The promising antibacterial activity of gallium both in vitro and in different animal models of infection raises the hope that gallium will confirm its efficacy in clinical trials, and will become a valuable therapeutic option to cure otherwise untreatable bacterial infections. PMID:24532037

Bonchi, Carlo; Imperi, Francesco; Minandri, Fabrizia; Visca, Paolo; Frangipani, Emanuela

2014-01-01

152

Two octanuclear gallium metallamacrocycles of topologically different connectivities.  

PubMed

Two topologically different metallamacrocycles--S8 symmetric octanuclear gallium(III) metalladiazamacrocycle and pseudo-D4 symmetric octanuclear gallium(III) metalladiazamacrocycle--could be prepared using two similar heteroditopic bridging ligands having asymmetrical tridentate-bidentate binding residues. PMID:18026590

Park, Mira; John, Rohith P; Moon, Dohyun; Lee, Kyungjin; Kim, Ghyung Hwa; Lah, Myoung Soo

2007-12-14

153

Gallium scintigraphy in bone infarction. Correlation with bone imaging  

SciTech Connect

The appearance of gallium-67 images in bone infarction was studied in nine patients with sickle cell disease and correlated with the bone scan findings. Gallium uptake in acute infarction was decreased or absent with a variable bone scan uptake, and normal in healing infarcts, which showed increased uptake on bone scan. The significance of these findings is discussed.

Armas, R.R.; Goldsmith, S.J.

1984-01-01

154

Automated realization of the gallium melting and triple points  

NASA Astrophysics Data System (ADS)

In order to improve the automation and convenience of the process involved in realizing the gallium fixed points, an automated apparatus, based on thermoelectric and heat pipe technologies, was designed and developed. This paper describes the apparatus design and procedures for freezing gallium mantles and realizing gallium melting and triple points. Also, investigations on the melting behavior of a gallium melting point cell and of gallium triple point cells were carried out while controlling the temperature outside the gallium point cells at 30 °C, 30.5 °C, 31 °C, and 31.5 °C. The obtained melting plateau curves show dentate temperature oscillations on the melting plateaus for the gallium point cells when thermal couplings occurred between the outer and inner liquid-solid interfaces. The maximum amplitude of the temperature fluctuations was about 1.5 mK. Therefore, the temperature oscillations can be used to indicate the ending of the equilibrium phase transitions. The duration and amplitude of such temperature oscillations depend on the temperature difference between the setting temperature and the gallium point temperature; the smaller the temperature difference, the longer the duration of both the melting plateaus and the temperature fluctuations.

Yan, X.; Duan, Y.; Zhang, J. T.; Wang, W.

2013-09-01

155

Role of gallium-67 in the clinical evaluation of cancer  

Microsoft Academic Search

This review is based primarily on historic data, and it examines the indications for and limitations of gallium-67 scanning in the evaluation of patients with neoplasms. The use of gallium-67 scans is discussed according to tumor type, and data from the most representative and comprehensive studies are included. The results described, some of which were obtained primarily with older imaging

C. Bekerman; P. B. Hoffer; J. D. Bitran

1984-01-01

156

A receptor-based bioassay for quantitative detection of gallium.  

PubMed

The detection of gallium in biological samples is required due to its role in the diagnosis of tumor and for possible treatment of malignancies. However, the use of purely instrumental techniques is unsuitable for detection of low levels of gallium in biological matrixes. We have synthesized new protein conjugates based on 4-(2-pyridylazo) ligands. The conjugates were successfully employed for the detection of gallium in biological matrixes using a nonantibody-based sandwich assay format. The recovery level obtained was between 97 and 101.3 with a relative standard deviation of less than 5%. The assay resulted in a detection limit of 5 x 10(-8) M and a remarkable selectivity for gallium(III) relative to other metals investigated. The new method provided adequate accuracy for gallium applicable for animal physiology and clinical toxicology. PMID:10596209

Xu, H; Lee, E; Sadik, O A; Bakhtiar, R; Drader, J; Hendrikson, C

1999-12-01

157

Solid-state gallium-69 and gallium-71 nuclear magnetic resonance spectroscopic studies of gallium analogue zeolites and related systems  

Microsoft Academic Search

The authors have obtained solid-state 11.7-T ⁶⁹Ga and ⁷¹Ga nuclear magnetic resonance (NMR) spectra of a series of gallosilicates (gallium analogues of zeolites Na-X, Na-Y, Na-sodalite, and Na-natrolite). From the apparent ⁶⁹Ga and ⁷¹Ga chemical shifts, values of the nuclear quadrupole coupling constants (e²qQ\\/h) and the true, isotropic chemical shifts (delta\\/sub i) have been deduced for the framework, tetrahedral, Ga(OSi)â

Hye Kyung C. Timken; Eric Oldfield

1987-01-01

158

The Preparation and Structural Characterization of Three Structural Types of Gallium Compounds Derived from Gallium (II) Chloride  

NASA Technical Reports Server (NTRS)

The three compounds Ga2Cl4(4-mepy)2 (1),[GaCl2(4-mepy)4]GaCl4x1/2(4-mepy); (2) and GaCl2(4-mepy)2(S2CNEt2); (3) (4-mepy= 4-methylpyridine) have been prepared from reactions of gallium (II) chloride in 4-methylpyridine and characterized by single-crystal X-ray analysis. Small variations in the reaction conditions for gallium(II) chloride can produce crystals with substantially different structural properties. The three compounds described here encompass a neutral gallium(II) dimer in which each gallium is four-coordinate, an ionic compound containing both anionic and cationic gallium complex ions with different coordination numbers and a neutral six-coordinate heteroleptic

Gordon, Edward M.; Hepp, Aloysius F.; Duraj. Stan A.; Habash, Tuhfeh S.; Fanwick, Phillip E.; Schupp, John D.; Eckles, William E.; Long, Shawn

1997-01-01

159

Gallium scintigraphic pattern in lung CMV infections  

SciTech Connect

Due to extensive use of prophylactic therapy for Pneumonitis Carinii Pneumonia (PCP), Cytomegalic Viral (CMV) infection may now be the most common lung infection in AIDS patients. This study was performed to determine Gallium-67 patterns in AIDS patients with CMV. Pathology reports were reviewed in AIDS patients who had a dose of 5 to 10 mCi of Gallium-67 citrate. Analysis of images were obtained 48-72 hours later of the entire body was performed. Gallium-67 scans in 14 AIDS patients with biopsy proven CMV, were evaluated for eye, colon, adrenal, lung and renal uptake. These were compared to 40 AIDS patients without CMV. These controls had infections including PCP, Mycobacterial infections, and lymphocytic interstitial pneumonitis. 100% of CMV patients had bowel uptake greater than or equal to liver. Similar bowel activity was seen in 50% of AIDS patients without CMV. 71% had intense eye uptake which was seen in only 10% of patients without CMV. 50% of CMV patients had renal uptake compared to 5% of non-CMV cases. Adrenal uptake was suggested in 50%, however, SPECT imaging is needed for confirmation. 85% had low grade lung uptake. The low grade lung had perihilar prominence. The remaining 15% had high grade lung uptake (greater than sternum) due to superimposed PCP infection. Colon uptake is very sensitive indicator for CMV infection. However, observing eye, renal, and or adrenal uptake improved the diagnostic specificity. SPECT imaging is needed to confirm renal or adrenal abnormalities due to intense bowel activity present in 100% of cases. When high grade lung uptake is seen superimposed PCP is suggested.

Ganz, W.I.; Cohen, D.; Mallin, W. [Univ. of Miami School of Medicine, FL (United States)] [and others

1994-05-01

160

Oxide formation during etching of gallium arsenide  

Microsoft Academic Search

Characterisation of n-type GaAs, etched in a 5:1:1 mixture of H2SO4:H2O2:H2O, was performed using X-ray photoelectron spectroscopy (XPS) and electrochemical AC impedance. Quantitative XPS analysis of GaAs indicated that the as-received wafers had a gallium-rich native oxide which was not affected by solvent degreasing treatments. Subsequent, oxidative etching formed a thinner arsenic-rich oxide. It is suggested that etching causes initial

D. Ghidaoui; S. B. Lyon; G. E. Thompson; J. Walton

2002-01-01

161

Strong field processes inside gallium arsenide  

NASA Astrophysics Data System (ADS)

We demonstrated experimentally that the multiphoton ionization rate in gallium arsenide depends on the alignment of the laser polarization with respect to the crystal axis. We observed modulation in the ionization rate of a linearly-polarized 1900 nm laser beam directly by measuring its transmission while rotating the crystal, without Fourier analysis. We propose that the modulation in the ionization rate arises from periodic variation in the reduced carrier mass, as predicted by Keldysh theory. We show direct comparison of the experimental transmission modulation depth with Keldysh?s non-resonant ionization theory for solids. This opens up a novel method for non-invasive crystallography of semiconductor materials.

Golin, S. M.; Kirkwood, S. E.; Klug, D. D.; Villeneuve, D. M.; Rayner, D. M.; Trallero Herrero, C. A.; Corkum, P. B.

2014-10-01

162

Behavior of Zircaloy Cladding in the Presence of Gallium  

SciTech Connect

The U.S. Department of Energy has established a dual-track approach to the disposition of plutonium arising from the dismantling of nuclear weapons. Both immobilization and reactor-based mixed-oxide (MOX) fuel technologies are being evaluated. The reactor-based MOX fuel option requires assessment of the potential impact of concentrations of gallium (on the order of 1 to 10 ppm), not present in conventional MOX fuel, on cladding material performance. An experimental program was designed to evaluate the performance of prototypic Zircaloy cladding materials against (1) liquid gallium, and (2) various concentrations of G~03. Three types of tests were performed: (1) corrosion, (2) liquid metal embrittlement, and (3) corrosion-mechanical. These tests were to determine corrosion mechanisms, thresholds for temperature and concentration of gallium that delineate behavioral regimes, and changes in the mechanical properties of Zircaloy. Results have generally been favorable for the use of weapons-grade (WG) MOX fhel. The Zircaloy cladding does react with gallium to form intermetallic compounds at >3000 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (parts per million) of gallium in the MOX fuel. Furthermore, no evidence for grain boundary penetration by gallium or liquid metal embrittlement was observed.

DiStefano, J.R.; King, J.F.; Manneschmidt, E.T.; Strizak, J.P.; Wilson, D.F.

1998-09-28

163

Mechanism of gallium-67 accumulation in tumors  

SciTech Connect

Neoplasms are characterized by increased perfusion, increased permeability of their capillary beds to macromolecules, and a delay in new lymphatic vessel growth. These lead to the increased entry and residency time of macromolecules in the interstitial space of tumors. Multiple factors contribute to the localization of /sup 67/Ga in tumors. Adequate blood supply is essential; at areas with no blood supply such as the necrotic center of a large tumor, there is no /sup 67/Ga accumulation. Gallium-67, mainly in the form of transferrin-67Ga complex, is delivered to the tumor through capillaries with increased permeability. In tumors, some /sup 67/Ga is taken up by tumor cells; some may also be taken up by inflammatory cells when they are present. Gallium-67 binding proteins, such as lactoferrin or ferritin, may also contribute to the accumulation and retention of /sup 67/Ga in tumors; however, their roles are less clear. The intensity of these various factors determine their relative contribution and the degree of /sup 67/Ga accumulation in tumors.56 references.

Tsan, M.F.; Scheffel, U.

1986-07-01

164

Measurement of the solar neutrino capture rate with gallium metal  

SciTech Connect

The solar neutrino capture rate measured by the Russian-American Gallium Experiment (SAGE) on metallic gallium during the period January 1990 through December 1997 is 67.2{sub {minus}7.0{minus}3.0}{sup +7.2+3.5} SNU, where the uncertainties are statistical and systematic, respectively. This represents only about half of the predicted standard solar model rate of 129 SNU. All the experimental procedures, including extraction of germanium from gallium, counting of {sup 71}Ge, and data analysis, are discussed in detail. {copyright} {ital 1999} {ital The American Physical Society}

SAGE Collaboration

1999-11-01

165

Microencapsulation of gallium-indium (Ga-In) liquid metal for self-healing applications.  

PubMed

Microcapsules containing a liquid metal alloy core of gallium-indium (Ga-In) are prepared via in situ urea-formaldehyde (UF) microencapsulation. The capsule size, shape, thermal properties, and shell wall thickness are investigated. We prepare ellipsoidal capsules with major and minor diameter aspect ratios ranging from 1.64 to 1.08 and with major diameters ranging from 245?µm to 3?µm. We observe that as the capsule major diameter decreases, the aspect ratio approaches 1. The thermal properties of the prepared microcapsules are investigated by thermogravimetric (TGA) and differential scanning calorimetry (DSC). Microcapsules are shown to survive incorporation into an epoxy matrix and to trigger via mechanical damage to the cured matrix. Microcapsules containing liquid metal cores may have diverse applications ranging from self-healing to contrast enhancement or the demonstration of mechano-adaptive circuitry. PMID:24495196

Blaiszik, B J; Jones, A R; Sottos, N R; White, S R

2014-01-01

166

Hyperfine Magnetic Field Measurements in the Heusler Alloys COBALT(2)-TITANIUM-Z, COBALT(2)-MAGNESIUM-Z (z = Silicon, Germanium, and Tin) and COBALT(2)-MAGNESIUM- Gallium Using the Moessbauer Effect (me) and the Time Differential Perturbed Angular Correlation (tdpac) Techniques  

NASA Astrophysics Data System (ADS)

Measurements of the hyperfine magnetic field in a series of Heusler alloys were performed. The probes were in (^{119}Sn) and cadmium (^{111}Cd). These measurements were performed at the University of Cincinnati in Cincinnati, Ohio. Two techniques were used. The first technique was the Mossbauer effect, which was used to measure the hyperfine magnetic field on ^{119 }Sn in Co_2TiZ (Z = Si, Ge, and Sn), and the second technique was the Time Differential Perturbed Angular Correlation which was used to measure the hyperfine magnetic field on ^ {111}Cd in the Co_2MnZ (Z = Si, Ge, Sn, and Ga). The probes are expected to go to the Z sites of the alloys. The hyperfine magnetic field measurements on ^{119}Sn in Co _2TiZ (Z = Si, Ge, and Sn) alloys were done at room, dry ice and liquid nitrogen temperatures by using the Mossbauer effect technique. The data were fitted by using a least squares fit from which three parameters were extracted. These parameters are the isomer shift, the quadrupole splitting and the hyperfine magnetic field. Temperature variation measurements of the hyperfine magnetic field were performed on ^{111 }Cd in Co_2MnZ (Z = Si, Ge, Sn, and Ga) alloys. The data were fitted again by using a least squares fit from which the Larmor frequency which is related to the hyperfine magnetic field was extracted. Also the Fourier Transforms were taken of the data, on the one hand to confirm the results of the least squares fit and on the other hand to look for more frequencies. Results of the Fourier Transforms show that some of the probe, ^{111}In, did go to the Co site in the Co_2MnZ (Z = Ga, Si, and Ge) alloys. The hmf on ^{111 }Cd in the Co site of these alloys is found to be 68 kOe which is consistent with the value found in the literature. Two theoretical models were examined for the trends of hyperfine magnetic field on ^{119 }Sn and ^{111}Cd in Co_2MnZ (Z = Si, Ge, Sn, and Ga) alloys. These are the Campbell and Blandin model and the Stearns' overlap model. Results show that the Campbell and Blandin model does predict the trends of the hyperfine magnetic field on ^{111}Cd but it fails in predicting any trends on ^ {119}Sn in Co_2MnZ (Z = Si, Ge, Sn, and Ga) alloys. The overlap model did not predict any trends of hmf on either probe in these alloys. A new relationship was found between the hyperfine magnetic field and the lattice constants of these alloys.

Lahamer, Amer Said

1990-01-01

167

Preliminary Experimental Measurements for a Gallium Electromagnetic (GEM) Thruster  

NASA Technical Reports Server (NTRS)

A low-energy gallium plasma source is used to perform a spatially and temporally broad spectroscopic survey in the 220-520 nm range. Neutral, singly, and doubly ionized gallium are present in a 20 J, 1.8 kA (peak) arc discharge operating with a central cathode. When the polarity of the inner electrode is reversed the discharge current and arc voltage waveforms remain similar. Utilizing a central anode configuration, multiple Ga lines are absent in the 270-340 nm range. In addition, neutral and singly ionized Fe spectral lines are present, indicating erosion of the outer electrode. With graphite present on the insulator to facilitate breakdown, line emission from the gallium species is further reduced and while emissions from singly and doubly ionized carbon atoms and molecular carbon (C2) radicals are observed. These data indicate that a significant fraction of energy is shifted from the gallium and deposited into the various carbon species.

Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

2007-01-01

168

GALLIUM--2000 30.1 By Deborah A. Kramer  

E-print Network

devices (LEDs, laser diodes, photodetectors, and solar cells) and ICs. Analog ICs were the largest end consumption rates. Free market gallium prices skyrocketed to reach $1,500 to $2,000 per kilogram, a level

169

Gallium accumulation in early pulmonary Pneumocystis carinii infection  

SciTech Connect

The accumulation of gallium 67 citrate in pulmonary Pneumocystis carinii is well known. The sensitivity of gallium uptake in detecting early inflammatory processes, even when conventional roentgenograms are normal, would seem to make it possible in immunocompromised patients to make a presumptive diagnosis of this serious infection early in its course without using invasive techniques to demonstrate the organism. However, the presence of gallium uptake in radiation pneumonitis, pulmonary drug toxicity, and other processes that also occur in this group limit its usefulness. In our two patients--a young woman with Hodgkin's disease and an elderly woman with small cell lung cancer--this technique proved helpful. Although the latter patient was successfully treated empirically, such empiric treatment should be reserved for patients unable or unwilling to undergo invasive tests. Pulmonary gallium uptake in patients with respiratory symptoms, even with a normal chest film, should prompt attempts to directly demonstrate the organism.

Stevens, D.A.; Allegra, J.C.

1986-09-01

170

Computer simulation of radiation damage in gallium arsenide  

NASA Technical Reports Server (NTRS)

A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging.

Stith, John J.; Davenport, James C.; Copeland, Randolph L.

1989-01-01

171

Gallium complexes with ?-diimine and phenazine in various reduced states.  

PubMed

Reaction of ?-diimine-stabilized "digallane" [Ga2L2] with phenazine (Phz) leads to gallium complexes in which Phz and ?-diimine show different reduced forms, demonstrating their noninnocence and diverse coordination modes. PMID:25472501

Zhao, Yanxia; Liu, Yanyan; Wang, Zeyi; Xu, Wenhua; Liu, Bin; Su, Ji-Hu; Wu, Biao; Yang, Xiao-Juan

2014-12-23

172

Gallium uptake by transferrin and interaction with receptor 1.  

PubMed

The kinetics and thermodynamics of Ga(III) exchange between gallium mononitrilotriacetate and human serum transferrin as well as those of the interaction between gallium-loaded transferrin and the transferrin receptor 1 were investigated in neutral media. Gallium is exchanged between the chelate and the C-site of human serum apotransferrin in interaction with bicarbonate in about 50 s to yield an intermediate complex with an equilibrium constant K (1) = (3.9 +/- 1.2) x 10(-2), a direct second-order rate constant k (1) = 425 +/- 50 M(-1) s(-1) and a reverse second-order rate constant k (-1) = (1.1 +/- 3) x 10(4) M(-1) s(-1). The intermediate complex loses a single proton with proton dissociation constant K (1a) = 80 +/- 40 nM to yield a first kinetic product. This product then undergoes a modification in its conformation which lasts about 500 s to produce a second kinetic intermediate, which in turn undergoes a final extremely slow (several hours) modification in its conformation to yield the gallium-saturated transferrin in its final state. The mechanism of gallium uptake differs from that of iron and does not involve the same transitions in conformation reported during iron uptake. The interaction of gallium-loaded transferrin with the transferrin receptor occurs in a single very fast kinetic step with a dissociation constant K (d) = 1.10 +/- 0.12 microM and a second-order rate constant k (d) = (1.15 +/- 0.3) x 10(10) M(-1) s(-1). This mechanism is different from that observed with the ferric holotransferrin and suggests that the interaction between the receptor and gallium-loaded transferrin probably takes place on the helical domain of the receptor which is specific for the C-site of transferrin and HFE. The relevance of gallium incorporation by the transferrin receptor-mediated iron-acquisition pathway is discussed. PMID:16988841

Chikh, Zohra; Ha-Duong, Nguyêt-Thanh; Miquel, Geneviève; El Hage Chahine, Jean-Michel

2007-01-01

173

The effect of copper and gallium compounds on ribonucleotide reductase  

SciTech Connect

The mode of action of copper complexes (CuL and CuKTS) and gallium compounds (gallium nitrate and citrate) in cytotoxicity was studied. The effects of these agents on the enzyme ribonucleotide reductase was investigated by monitoring the tyrosyl free radical present in the active site of the enzyme through electron spin resonance (ESR) spectroscopy. Ribonucleotide reductase, a key enzyme in cellular proliferation, consists of two subunits. M1, a dimer of molecular weight 170,000 contains the substrate and effector binding sites. M2, a dimer of molecular weight 88,000, contains non-heme iron and tyrosyl free radical essential for the activity of the enzyme. In studies using copper complexes, the cellular oxidative chemistry was examined by ESR studies on adduct formation with membranes, and oxidation of thiols. Membrane thiols were oxidized through the reduction of the ESR signal of the thiol adduct and the analysis of sulfhydryl content. Using the radiolabel [sup 59]Fe, the inhibitory action of copper thiosemicarbazones on cellular iron uptake was shown. The inhibitory action of CuL on ribonucleotide reductase was shown by the quenching of the tyrosyl free radical on the M2 subunit. The hypothesis that gallium directly interacts with the M2 subunit of the enzyme and displaces the iron from it was proven. The tyrosyl free radical signal from cell lysates was inhibited by the direct addition of gallium compounds. Gallium content in the cells was measured by a fluorimetric method, to ensure the presence of sufficient amounts of gallium to compete with the iron in the M2 subunit. The enzyme activity, measured by the conversion of [sup 14]C-CDP to the labeled deoxy CDP, was inhibited by the addition of gallium nitrate in a cell free assay system. The immunoprecipitation studies of the [sup 59]Fe labeled M2 protein using the monoclonal antibody directed against this subunit suggested that gallium releases iron from the M2 subunit.

Narasimhan, J.

1992-01-01

174

MTAMAGNTI SME DU GRENAT D'ERBIUM ET DE GALLIUM  

E-print Network

281 M�TAMAGN�TI SME DU GRENAT D'ERBIUM ET DE GALLIUM J. P. REDOULES, P. CARRARA, A. R. FERT, M. C gallate d'erbium suivant les trois directions [001], [011] et [111], à une température voisine de 0,080 °K modèle d'Ising. Abstract. 2014 Experimental study of the metamagnetism of erbium gallium garnet along

Paris-Sud XI, Université de

175

Complexometric determination of gallium with calcein blue as indicator  

USGS Publications Warehouse

A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1 % and a relative standard deviation of about 0.4% for 10 mg of gallium. ?? 1967.

Elsheimer, H.N.

1967-01-01

176

Mechanism of gallium-67 accumulation in inflammatory lesions  

Microsoft Academic Search

Multiple factors contribute to the accumulation and retention of gallium-67 in inflammatory lesions. Adequate blood supply is essential. Gallium-67, mainly in the form of transferrin-Ga-67 complex, is delivered to the inflammatory lesions through capillaries with increased permeability. At the site of inflammation, some Ga-67 is taken up by leukocytes and bacteria when they are present. In addition, Ga-67 may also

Min-Fu Tsan

1985-01-01

177

Generator for ionic gallium-68 based on column chromatography  

DOEpatents

A physiologically acceptable solution of gallium-68 fluorides, having an activity of 0.1 to 50 millicuries per milliliter of solution is provided. The solution is obtained from a generator comprising germanium-68 hexafluoride bound to a column of an anion exchange resin which forms gallium-68 in situ by eluting the column with an acid solution to form a solution containing .sup.68 Ga-fluorides. The solution then is neutralized prior to administration.

Neirinckx, Rudi D. (Medfield, MA); Davis, Michael A. (Westwood, MA)

1981-01-01

178

Hybrid Spintronic Structures With Magnetic Oxides and Heusler Alloys  

Microsoft Academic Search

Hybrid spintronic structures, integrating half-metallic magnetic oxides and Heusler alloys with their predicted high spin polarization, are important for the development of second-generation spintronics with high-efficient spin injection. We have synthesized epitaxial magnetic oxide Fe 3O 4 on GaAs(100) and the unit cell of the Fe3O4 was found to be rotated by 45deg to match the gallium arsenide GaAs. The

Y. B. Xu; S. S. A. Hassan; P. K. J. Wong; J. Wu; J. S. Claydon; Y. X. Lu; C. D. Damsgaard; J. B. Hansen; C. S. Jacobsen; Y. Zhai; G. van der Laan; R. Feidenhans; S. N. Holmes

2008-01-01

179

Inhalation developmental toxicology studies: Gallium arsenide in mice and rats  

SciTech Connect

Gallium arsenide is a crystalline compound used extensively in the semiconductor industry. Workers preparing solar cells and gallium arsenide ingots and wafers are potentially at risk from the inhalation of gallium arsenide dust. The potential for gallium arsenide to cause developmental toxicity was assessed in Sprague- Dawley rats and CD-1 (Swiss) mice exposed to 0, 10, 37, or 75 mg/m{sup 3} gallium arsenide, 6 h/day, 7 days/week. Each of the four treatment groups consisted of 10 virgin females (for comparison), and {approx}30 positively mated rats or {approx}24 positively mated mice. Mice were exposed on 4--17 days of gestation (dg), and rats on 4--19 dg. The day of plug or sperm detection was designated as 0 dg. Body weights were obtained throughout the study period, and uterine and fetal body weights were obtained at sacrifice (rats, 20 dg; mice, 18 dg). Implants were enumerated and their status recorded. Live fetuses were sexed and examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. Gallium and arsenic concentrations were determined in the maternal blood and uterine contents of the rats (3/group) at 7, 14, and 20 dg. 37 refs., 11 figs., 30 tabs.

Mast, T.J.; Greenspan, B.J.; Dill, J.A.; Stoney, K.H.; Evanoff, J.J.; Rommereim, R.L.

1990-12-01

180

Method of fabricating germanium and gallium arsenide devices  

NASA Technical Reports Server (NTRS)

A method of semiconductor diode fabrication is disclosed which relies on the epitaxial growth of a precisely doped thickness layer of gallium arsenide or germanium on a semi-insulating or intrinsic substrate, respectively, of gallium arsenide or germanium by either molecular beam epitaxy (MBE) or by metal-organic chemical vapor deposition (MOCVD). The method involves: depositing a layer of doped or undoped silicon dioxide on a germanium or gallium arsenide wafer or substrate, selectively removing the silicon dioxide layer to define one or more surface regions for a device to be fabricated thereon, growing a matched epitaxial layer of doped germanium or gallium arsenide of an appropriate thickness using MBE or MOCVD techniques on both the silicon dioxide layer and the defined one or more regions; and etching the silicon dioxide and the epitaxial material on top of the silicon dioxide to leave a matched epitaxial layer of germanium or gallium arsenide on the germanium or gallium arsenide substrate, respectively, and upon which a field effect device can thereafter be formed.

Jhabvala, Murzban (inventor)

1990-01-01

181

Merits of gallium nitride based power conversion  

NASA Astrophysics Data System (ADS)

Gallium nitride (GaN) based power electronics devices are actively being evaluated to determine if their theoretical advantages over silicon (Si) based switches can translate into improved performance of existing hardware as well as open the doors to new types of applications, such as high temperature implementations, or very high frequency power conversion. The following paper presents an overview of this activity. A brief summary about power electronics and the requirements of semiconductor devices used in this field is provided. Detailed analysis of the advantages and the challenges of using GaN devices is included along with a survey of demonstrations. This work also presents the test results from the evaluation of GaN devices from Efficient Power Conversion (EPC) and Transphorm. Included is a demonstration of EPC’s devices in a high frequency, high efficiency, switched-capacitor voltage doubler. This circuit achieves an output of 480 W at a switching frequency of 893 kHz.

Scott, Mark J.; Fu, Lixing; Zhang, Xuan; Li, Jinzhu; Yao, Chengcheng; Sievers, Markus; Wang, Jin

2013-07-01

182

The Soviet-American Gallium Experiment (SAGE)  

SciTech Connect

It is a great pleasure for me to have been asked by Louis Rosen to tell you about the Soviet-American Gallium Experiment (SAGE). This undertaking is a multi-institutional collaboration among scientists from the Institute for Nuclear Research, Moscow (INR), Los Alamos National Laboratory (LANL), and several US universities. Its purpose is to measure the number of low-energy electron neutrinos emitted from the Sun that arrive at this planet. As such, it is an extremely important experiment, touching on fundamental physics issues as well as solar dynamics. In contrast to the strategic overviews, plans, and hopes for international collaboration presented earlier today, SAGE is an ongoing working effort with high hopes of producing the first measurement of the Sun's low-energy neutrino flux. This paper reviews this experiment. 3 refs., 3 figs.

Garvey, G.T.

1989-01-01

183

Gallium-68 lipophilic complexes for labeling platelets  

SciTech Connect

Generator produced 68Ga-labeled platelets could be useful for positron emission tomographic (PET) studies of thrombosis or atherosclerosis. To label platelets with 68Ga, we have studied the effects of trace metals in elutions of 68Ga from 68Ge. Studies were conducted on the formation of lipophilic 68Ga complexes 8-hydroxyquinoline, tropolone, and mercaptopyridine-N-oxide (MPO). Parameters such as pH, buffers, concentration of ligand, and stability with time were investigated. High performance liquid chromatography and instant thin layer chromatography were used to quantitate formation of the 68Ga complex. Platelets from human, dog, and rabbit plasma were incubated with the 68Ga complexes and the percent labeling determined. Accumulation of platelets in the catheter scraped aorta of the rabbit was determined by PET imaging, tissue counting, and autoradiography. Gallium-68 MPO gave 40-60% labeling of rabbit platelets with higher accumulation in the scraped aorta compared to the normal.

Yano, Y.; Budinger, T.F.; Ebbe, S.N.; Mathis, C.A.; Singh, M.; Brennan, K.M.; Moyer, B.R.

1985-12-01

184

Direct Band Gap Wurtzite Gallium Phosphide Nanowires  

PubMed Central

The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555–690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

2013-01-01

185

Gallium Arsenide solar cell radiation damage experiment  

NASA Technical Reports Server (NTRS)

Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

1991-01-01

186

Cavity optomechanics in gallium phosphide microdisks  

SciTech Connect

We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8?×?10{sup 5} and mode volumes <10(?/n){sup 3}, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0?×?10{sup 4} intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5??m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g{sub 0}/2??30?kHz for the fundamental mechanical radial breathing mode at 488?MHz.

Mitchell, Matthew; Barclay, Paul E., E-mail: pbarclay@ucalgary.ca [Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada); Hryciw, Aaron C. [National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada)

2014-04-07

187

Cavity optomechanics in gallium phosphide microdisks  

E-print Network

Gallium phosphide microdisk optical microcavities with intrinsic quality factors > 280,000 and mode volumes < (10 lambda/n)^3 are demonstrated, and their nonlinear and optomechanical properties are studied. For optical intensities up to 350,000 intracavity photons, optical loss within the microcavity is observed to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two photon absorption is not significant. Optomechanical coupling between several mechanical resonances and the optical modes of the microdisk is observed, and an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g_0~80 kHz is measured for the 488 MHz mechanical fundamental radial breathing mode.

Mitchell, Matthew; Barclay, Paul E

2013-01-01

188

Radiation damage of gallium arsenide production cells  

NASA Technical Reports Server (NTRS)

High-efficiency gallium arsenide cells, made by the liquid epitaxy method (LPE), have been irradiated with 1-MeV electrons up to fluences of 10 to the 16th e/sq cm. Measurements have been made of cell spectral response and dark and light-excited current-voltage characteristics and analyzed using computer-based models to determine underlying parameters such as damage coefficients. It is possible to use spectral response to sort out damage effects in the different cell component layers. Damage coefficients are similar to other reported in the literature for the emitter and buffer (base). However, there is also a damage effect in the window layer and possibly at the window emitter interface similar to that found for proton-irradiated liquid-phase epitaxy-grown cells. Depletion layer recombination is found to be less than theoretically expected at high fluence.

Mardesich, N.; Garlick, G. F. J.

1987-01-01

189

Cavity optomechanics in gallium phosphide microdisks  

E-print Network

We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors $ > 2.8\\times10^{5}$ and mode volumes $< 10 (\\lambda/n)^3$, and study their nonlinear and optomechanical properties. For optical intensities up to $8.0\\times10^4$ intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5 $\\mu$m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate $g_0/2\\pi \\sim 30$ kHz for the fundamental mechanical radial breathing mode at 488 MHz.

Matthew Mitchell; Aaron C. Hryciw; Paul E. Barclay

2014-05-29

190

Gallium arsenide solar array subsystem study  

NASA Technical Reports Server (NTRS)

The effects on life cycle costs of a number of technology areas are examined for a gallium arsenide space solar array. Four specific configurations were addressed: (1) a 250 KWe LEO mission - planer array; (2) a 250 KWe LEO mission - with concentration; (3) a 50 KWe GEO mission planer array; (4) a 50 KWe GEO mission - with concentration. For each configuration, a baseline system conceptual design was developed and the life cycle costs estimated in detail. The baseline system requirements and design technologies were then varied and their relationships to life cycle costs quantified. For example, the thermal characteristics of the baseline design are determined by the array materials and masses. The thermal characteristics in turn determine configuration, performance, and hence life cycle costs.

Miller, F. Q.

1982-01-01

191

Detached growth of gallium doped germanium  

NASA Astrophysics Data System (ADS)

Detached Bridgman growth of gallium-doped germanium itself as well as the transition from detached to attached growth was observed in-situ for the first time, using a quartz-glass ampoule in a mirror furnace. Crystal diameter was 9 mm, the growth length 41 mm, and the growth velocity 0.5 mm/min. Undoped 1 1 1-oriented germanium served as seed material; the melt was doped with gallium ( C0=8.2×10 18 at/cm 3). Detachment took place after a growth length of 7 mm and continued for 27 mm; the remaining 7 mm grew with wall contact again. The wall-free growth could be observed around the entire circumference except for some small bridges (width: a few tens of micrometers, length: some hundreds of micrometers), where the crystal grew in contact with the wall. In the detached-grown part of the crystal, the 1 1 1-related growth lines are clearly visible. The transition from attached to detached growth and vice versa did not take place along a straight line but transitioned as islands over a length of about 1 mm. The gap between the growing crystal and the container wall varied between 10 and 80 ?m, as measured by a profilometer. The etch pit density is greatly reduced in the part of the crystal that grew free of the wall. An increase in the EPD is seen in the area where the crystal had contact with the ampoule wall by the bridges described above.

Dold, P.; Szofran, F. R.; Benz, K. W.

2002-01-01

192

An Asynchronous Microprocessor in Gallium Jos'e A. Tierno Alain J. Martin Drazen Borkovic  

E-print Network

An Asynchronous Microprocessor in Gallium Arsenide Jos'e A. Tierno Alain J. Martin Drazen Borkovic November 9, 1993 Abstract In this paper, several techniques for designing asynchronous circuits in Gallium

Martin, Alain

193

Electronic behavior of calcined material obtained from a gallium-N-phenylene-N hybrid copolymer  

SciTech Connect

Calcination of a gallium-N-phenylene-N hybrid copolymer under an argon atmosphere gave nano-sized gallium nitride-carbon cluster composite material. ESR spectral examinations of the calcined materials reveals the possibility of an electron transfer in the process of gallium nitride {yields} carbon clusters with an oxidation site at gallium nitride particles and a reduction site at carbon clusters. The calcined material was found to reduce methylene blue under visible light irradiation.

Matsui, H. [Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Yamamoto, S. [Taki Chemical Co. Ltd., 64-1, Nishiwaki, Befu-cho, Kakogawa, Hyogo 675-0125 (Japan); Hama, T. [Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Karuppuchamy, S. [Molecular Engineering Institute, Kinki University, 11-6, Kayanomori, Iizuka, Fukuoka 820-8555 (Japan)], E-mail: chamy@me-henkel.fuk.kindai.ac.jp; Yoshihara, M. [Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Molecular Engineering Institute, Kinki University, 11-6, Kayanomori, Iizuka, Fukuoka 820-8555 (Japan)

2008-01-08

194

Pure silver ohmic contacts to N- and P- type gallium arsenide materials  

DOEpatents

Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components an n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffused layer and the substrate layer, wherein the n-type layer comprises a substantially low doping carrier concentration.

Hogan, Stephen J. (Golden, CO)

1986-01-01

195

Journal of Crystal Growth 286 (2006) 197204 Low-temperature atomic assembly of stoichiometric gallium arsenide  

E-print Network

gallium arsenide from equiatomic vapor D.A. MurdickÃ?, X.W. Zhou, H.N.G. Wadley Department of Materials amorphous structure. The atomic assembly mechanisms of arsenic dimer incorporation, as well as gallium. Atomic processes responsible for the formation of the gallium vacancy defects were observed

Wadley, Haydn

196

SHOCK HUGONIOT AND MELT CURVE FOR A MODIFIED EMBEDDED ATOM METHOD MODEL OF GALLIUM  

E-print Network

SHOCK HUGONIOT AND MELT CURVE FOR A MODIFIED EMBEDDED ATOM METHOD MODEL OF GALLIUM F. J. Cherne. Molecular dynamics (MD) simulations have been performed on the complex material gallium us- ing a literature be obtained through a slight modification of the MEAM parameters. INTRODUCTION Gallium is a complex element

Duisburg-Essen, Universität

197

Analysis of the growth modes for gallium arsenide metalorganic vapor-phase epitaxy  

E-print Network

Analysis of the growth modes for gallium arsenide metalorganic vapor-phase epitaxy D. C. Law March 2000 The surface roughness of gallium arsenide 001 films produced by metalorganic vapor for gallium surface diffusion has been estimated: Ed 1.35 0.1 eV. © 2000 American Institute of Physics. S0021

Li, Lian

198

COUCHES PITAXIALES D'ARSNIURE DE GALLIUM OBTENUES PAR LA TECHNIQUE DE TRANSPORT EN PHASE VAPEUR  

E-print Network

161. COUCHES �PITAXIALES D'ARS�NIURE DE GALLIUM OBTENUES PAR LA TECHNIQUE DE TRANSPORT EN PHASE gallium sur des supports de germanium réalisée par la technique de transport en phase vapeur. Cette étude mobilité. Abstract. 2014 We have studied the epitaxy of gallium arsenide deposited by the vapor phase

Paris-Sud XI, Université de

199

Molten Gallium as a Catalyst for the Large-Scale Growth of Highly Aligned Silica Nanowires  

E-print Network

Molten Gallium as a Catalyst for the Large-Scale Growth of Highly Aligned Silica Nanowires Zheng. In this article, we show that the large size (5-50 µm in diameter), low melting point gallium droplets can be used. Unlike any previously observed results using gold or iron as catalyst, the gallium-catalyzed VLS growth

Wang, Zhong L.

200

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting  

E-print Network

#12;Unusual strategies for using indium gallium nitride grown on silicon (111) for solid with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements and scal- able means to integrate these devices in modules for white light generation. gallium nitride

Rogers, John A.

201

Terahertz Kerr effect in gallium phosphide crystal M. Cornet,1,2  

E-print Network

Terahertz Kerr effect in gallium phosphide crystal M. Cornet,1,2 J. Degert,1,2, * E. Abraham,1 of the Kerr effect induced by an intense terahertz pulse in a h100i gallium phosphide crystal. The temporal in lithium niobate [5] and bulk n-GaAs [6]. Hereafter we report on the observation of TKE in a gallium

202

Spectral Data for Gallium: Ga I through Ga XXXI T. Shiraia...  

E-print Network

Spectral Data for Gallium: Ga I through Ga XXXI T. Shiraia... Naka Fusion Research Establishment April 2006; published online 23 May 2007 The energy levels and spectral lines of gallium atom in all spectral lines; emission spectra; Ga; gallium ions; ground states; ionization potentials; multiply charged

Magee, Joseph W.

203

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting  

E-print Network

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements and scal- able means to integrate these devices in modules for white light generation. gallium nitride

Choquette, Kent

204

Gallium phosphide photonic crystal nanocavities in the visible Kelley Rivoire,a  

E-print Network

Gallium phosphide photonic crystal nanocavities in the visible Kelley Rivoire,a Andrei Faraon at visible wavelengths are fabricated in a high refractive index n 3.2 gallium phosphide membrane fabrication proce- dures for semiconductors such as silicon and gallium ars- enide, which have band gaps

Faraon, Andrei

205

Oxide-assisted growth and optical characterization of gallium-arsenide nanowires  

E-print Network

Oxide-assisted growth and optical characterization of gallium-arsenide nanowires W. S. Shi, Y. FAs nanowires. © 2001 American Institute of Physics. DOI: 10.1063/1.1371966 Gallium arsenide GaAs , as a direct mol % gallium oxide Ga2O3 at room temperature. The target and a polished silicon 100 substrate were

Zheng, Yufeng

206

Title of Document: GALLIUM NITRIDE NANOWIRE BASED ELECTRONIC AND OPTICAL DEVICES.  

E-print Network

ABSTRACT Title of Document: GALLIUM NITRIDE NANOWIRE BASED ELECTRONIC AND OPTICAL DEVICES. Abhishek and Computer Engineering Gallium nitride nanowires have significant potential for developing nanoscale emitters nm electroluminescence with a full width half maximum of 25 nm at 300 K. #12;GALLIUM NITRIDE NANOWIRE

Anlage, Steven

207

Gallium and Indium Complexes for Ring-Opening Polymerization of Cyclic Ethers, Esters and Carbonates  

E-print Network

1 Gallium and Indium Complexes for Ring-Opening Polymerization of Cyclic Ethers, Esters-francois.carpentier@univ-rennes1.fr Contents 1. Introduction 2. Gallium-based initiators/catalysts for the ROP of cyclic ethers, esters and carbonates: synthesis, characterization and catalytic performance 2.1. Gallium complexes

Paris-Sud XI, Université de

208

PHNOMNES DE RELAXATION DANS LES STRUCTURES PLANES PITAXIALES A L'ARSNIURE DE GALLIUM  

E-print Network

1679 PH�NOM�NES DE RELAXATION DANS LES STRUCTURES PLANES �PITAXIALES A L'ARS�NIURE DE GALLIUM P fréquences dans les structures planes épitaxiales, avec ou sans grille, en arséniure de gallium sur substrat place on both gated and ungated gallium arsenide planar epitaxial structure are discussed. The voltage

Paris-Sud XI, Université de

209

Cross-Section High Resolution Transmission Electron Microscopy Investigation of Internal Structures of Gallium Nitride Nanowires  

E-print Network

of Gallium Nitride Nanowires Benjamin W. Jacobs1 , Kaylee McElroy2 , Raed Al-Duhaileb3 , Martin A Crimp4 Michigan State University, East Lansing, Michigan, USA e-mail: ayresv@msu.edu Abstract-Gallium nitride blocks with properties enhanced by their small size and large aspect ratios. Gallium nitride (Ga

Ayres, Virginia

210

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells  

E-print Network

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been with a larger number of vacancies, that facilitates indium and gallium diffusion, in the sodium free films

Rockett, Angus

211

GALLIUM--2002 29.1 References that include a section mark () are found in the Internet  

E-print Network

GALLIUM--2002 29.1 1 References that include a section mark (§) are found in the Internet References Cited section. GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared two large high-grade zones of gallium mineralization with average grades in excess of 100 grams per

212

HOT CARRIER SPACE AND TIME DEPENDENT TRANSIENTS IN SHORT CHANNEL GALLIUM ARSENIDE DEVICES55  

E-print Network

HOT CARRIER SPACE AND TIME DEPENDENT TRANSIENTS IN SHORT CHANNEL GALLIUM ARSENIDE DEVICES55 Hr in gallium arsenide when the fields change temporally and spatially at a finite rate. For temporal changes phénomènes transitoires de transport dans l'arseniure de gallium lorsque les champs varient dans le temps et

Paris-Sud XI, Université de

213

LE JOURNAL DE PHYSIQUE STARK BROADENING OF NEUTRAL AND SINGLY IONIZED GALLIUM AND INDIUM  

E-print Network

703 LE JOURNAL DE PHYSIQUE STARK BROADENING OF NEUTRAL AND SINGLY IONIZED GALLIUM AND INDIUM LINES, accepte Ie 19 fivrier 1987) Résumé : Les élargissements Stark de raies du gallium et de l'indium neutre cathode liquide utilisant un mélange sodium-indium ou potassium-gallium, la densité electronique pouvant

Paris-Sud XI, Université de

214

May 20, 2010 Growing gallium arsenide in thick multilayer stacks could make a big  

E-print Network

optics.org NEWS May 20, 2010 Growing gallium arsenide in thick multilayer stacks could make a big the technique for gallium arsenide (GaAs), the team hopes that its method will be equally applicable to other material systems such as gallium nitride and indium phosphide (Nature 465 329). "We can generate compound

Rogers, John A.

215

Theoretical study of sequential oxidation of clusters of gallium oxide: Ga3On (n: 48)  

E-print Network

Theoretical study of sequential oxidation of clusters of gallium oxide: Ga3On (n: 4­8) S. Gowtham of gallium oxide clusters from Ga3O4 to Ga3O8. These results, based on density functional theory calculations clusters of gallium oxide can be taken as a model to understand the physics and chemistry of nanostructures

Pandey, Ravi

216

Surface reconstructions of cubic gallium nitride ,,001... grown by radio frequency nitrogen plasma molecular beam epitaxy  

E-print Network

Surface reconstructions of cubic gallium nitride ,,001... grown by radio frequency nitrogen plasma molecular beam epitaxy under gallium-rich conditions Muhammad B. Haider, Rong Yang, Costel Constantin; published online 27 October 2006 Cubic GaN has been grown under gallium Ga -rich growth conditions using

217

Nanoporous gallium nitride square microtubes Yucheng Lan Hui Wang Feng Lin  

E-print Network

Nanoporous gallium nitride square microtubes Yucheng Lan · Hui Wang · Feng Lin · Yalin Lu · Yang Li / Published online: 23 July 2013 � Springer Science+Business Media New York 2013 Abstract Porous gallium nitride microtubes were self- fabricated from gallium nitride submicron irregular struc- tures

Bao, Jiming

218

Experimental and numerical study of anomalous thermocapillary convection in liquid gallium  

E-print Network

Experimental and numerical study of anomalous thermocapillary convection in liquid gallium Janis 1998; accepted 2 August 1999 Thermocapillary Marangoni convection of liquid gallium was studied of the liquid gallium for a very long time. The convective flow at the free surface was found to be directed

Gelfgat, Alexander

219

Electrochemical passivation of gallium arsenide surface with organic self-assembled monolayers in aqueous electrolytes  

E-print Network

Electrochemical passivation of gallium arsenide surface with organic self-assembled monolayers-assembled monolayers of octadecylthiol ODT were reconstituted on freshly etched gallium arsenide (n on electro-optical devices.1,2 Among various semiconductors, gallium arsenide GaAs is a promising material

Deutschmann, Rainer

220

IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption  

E-print Network

IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption flat gallium arsenide solar cell, we show that it is possible to modify the flow of light and enhance material which directly contributes to the pho- tocurrent enhancement of the solar cell. Index Terms--Gallium

Grandidier, Jonathan

221

Gallium solar neutrino experiments: Absorption cross sections, neutrino spectra, and predicted event rates  

E-print Network

Gallium solar neutrino experiments: Absorption cross sections, neutrino spectra, and predicted that a spline fit determines accurately the event rates in a gallium detector even if new physics changes number s : 26.65. t, 12.15.Ff, 14.60.Pq, 96.60.Jw I. INTRODUCTION Gallium solar neutrino experiments are

Bahcall, John

222

Physica B 338 (2003) 159164 Fabrication and properties of gallium metallic  

E-print Network

Physica B 338 (2003) 159­164 Fabrication and properties of gallium metallic photonic crystals V City, UT 84112, USA Abstract Gallium metallic photonic crystals with 100% filling factor have been fabricated via infiltration of liquid gallium into opals of 300-nm silica spheres using a novel high pressure

Kozhevnikov, Vladimir

223

THE RAMAN SPECTRUM OF GALLIUM PHOSPHIDE By R. S. KRISHNAN and N. KRISHNAMURTHY,  

E-print Network

630. THE RAMAN SPECTRUM OF GALLIUM PHOSPHIDE By R. S. KRISHNAN and N. KRISHNAMURTHY, Department ordre du phosphure de gallium, récemment enre- gistrés par Russell et Hobden en utilisant un laser He of gallium phosphide recorded recently by Russell and Hobden using a He-Ne laser source, are discussed

Boyer, Edmond

224

Catalyst-Free Gallium Nitride Nanowire Nucleation Faculty Advisor: Dr. Virginia M. Ayres  

E-print Network

Catalyst-Free Gallium Nitride Nanowire Nucleation Faculty Advisor: Dr. Virginia M. Ayres Friday catalyst particles are not desirable. This thesis deals exclusively with gallium nitride catalyst free Investigation of Gallium Nitride Nanowires," International Journal of Nanomanufacturing, in press 2009. B. W

Ayres, Virginia

225

Solid-state gallium-69 and gallium-71 nuclear magnetic resonance spectroscopic studies of gallium analogue zeolites and related systems  

SciTech Connect

The authors have obtained solid-state 11.7-T /sup 69/Ga and /sup 71/Ga nuclear magnetic resonance (NMR) spectra of a series of gallosilicates (gallium analogues of zeolites Na-X, Na-Y, Na-sodalite, and Na-natrolite). From the apparent /sup 69/Ga and /sup 71/Ga chemical shifts, values of the nuclear quadrupole coupling constants (e/sup 2/qQ/h) and the true, isotropic chemical shifts (delta/sub i) have been deduced for the framework, tetrahedral, Ga(OSi)/sub 4/ sites. The e/sup 2/qQ/h values are in the range 1.9-2.7 MHz for /sup 69/Ga and 1.2-1.7 MHz for /sup 71/Ga. The isotropic chemical shifts are all in the range 171-186 ppm downfield from an external standard of 1 M Ga(NO/sub 3/)/sub 3/. Their results indicate that measurement of the apparent (second-order shifted) chemical shifts for pairs of isotopes of nonintegral spin quadrupolar nuclei in solids at one magnetic field strength is a useful new approach for determination of both isotropic chemical shifts and nuclear quadrupole coupling constant values.

Timken, H.K.; Oldfield, E.

1987-12-09

226

Simulation assisted design of a gallium phosphide np photovoltaic junction Charles R. Allen, Jong-Hyeok Jeon , Jerry M. Woodall  

E-print Network

Simulation assisted design of a gallium phosphide n­p photovoltaic junction Charles R. Allen, Jong February 2010 Keywords: Gallium phosphide Solar cell Multi-junction CPV Simulation a b s t r a c t A gallium phosphide photovoltaic junction is reported. Using a n­p structure, a gallium phosphide junction

Woodall, Jerry M.

227

Journal of Crystal Growth 310 (2008) 579583 Red shift in the photoluminescence of indium gallium arsenide nitride  

E-print Network

Journal of Crystal Growth 310 (2008) 579­583 Red shift in the photoluminescence of indium gallium gallium arsenide nitride (InGaAsN) in 1.0 � 10�6 Torr of nitrogen trifluoride (NF3) has been studied-phase epitaxy; B1. Nitrogen trifluoride; B2. Indium gallium arsenide nitride 1. Introduction Indium gallium

Hicks, Robert F.

228

Energy deposition in gallium arsenide. Final report  

SciTech Connect

This report pertains to the single-event-upset phenomena in microelectronic circuits with emphasis on those resulting from nuclear reactions induced by energetic protons. The goal is to understand the detailed physical mechanisms leading to SEUs sufficiently to put calculating SEUs on a sound quantitative basis. The author previously had considerable success in predicting the charge generation in well defined slabs of silicon. The purpose of this contract was to try extending the model and the associated simulation codes to GaAs and to begin the experimental measurements necessary to test them. The Clarkson Nuclear Reaction models were modified to handle proton-induced nuclear reactions in gallium arsenide. The codes were immediately useful in analyzing the significance that the edge-effect phenomena, discovered in microbeam studies of GaAs gates, would play in increasing the SEU rates for GaAs memories. Techniques were developed using these codes for calculating SEU rates for select circuits flown in space. Two of these circuits, the 2901B and the 93L422, are responsible for SEU problems aboard US satellites. Charge-collection Measurements were carried out using the GaAs Fat-FET test structures from the Rockwell memories.

McNulty, P.J.

1985-11-12

229

Gallium arsenide photo-field emission  

NASA Astrophysics Data System (ADS)

The development of monochromatic ultrafast electron sources with high brightness and high coherence is increasingly important in both time-resolved and energy-resolved electron microscopy. This work details the fabrication of intrinsic Gallium-Arsenide photo-field emitters and their evaluation as potential source candidates. The emitters were prepared via chemical etching and vacuum heat cleansing of cleaved wafer shards that had been mounted in refractory metal holders. Data were recorded in the form of field emission images, current-voltage characteristic curves and energy distribution curves under several different thermal and illumination conditions. As expected, illumination increased emission by 3 orders of magnitude. However a much larger than expected energy distribution of 0.76 eV was observed. This result invalidated presumptions that the band structure would produce a maximum energy width equal to the energy bandgap minus the photon energy. Following the experiment a Spicer-like 3-step model was used to explain this discrepancy. In the model the energy broadening is attributed to a combination of bulk thermal effects and surface band bending. Using this model, predictions are made as to the performance of a similar photo-field emitter that should better fulfill the needs of both time-resolved and energy-resolved electron microscopy.

Vecchione, Theodore

230

Reactive ion etching of gallium nitride films  

NASA Astrophysics Data System (ADS)

Reactive ion etching (RIE) was performed on gallium nitride (GaN) films grown by electron cyclotron resonance (ECR) plasma assisted molecular beam epitaxy (MBE). Etching was carried out using trifluoromethane (CHF3) and chloropentafluoroethane (C2ClF5) plasmas with Ar gas. A conventional rf plasma discharge RIE system without ECR or Ar ion gun was used. The effects of chamber pressure, plasma power, and gas flow rate on the etch rates were investigated. The etch rate increased linearly with the ratio of plasma power to chamber pressure. The etching rate varied between 60 and 500Å/min, with plasma power of 100 to 500W, chamber pressure of 60 to 300 mTorr, and gas flow rate of 20 to 50 seem. Single crystalline GaN films on sapphire showed a slightly lower etch rate than domain-structured GaN films on GaAs. The surface morphology quality after etching was examined by atomic force microscopy and scanning electron microscopy.

Lee, Heon; Oberman, David B.; Harris, James S.

1996-05-01

231

Characteristics of epitaxial garnets grown by CVD using single metal alloy sources. [Chemical Vapor Deposition  

NASA Technical Reports Server (NTRS)

Single metal alloys have been explored as the cation source in the chemical vapor deposition (CVD) of iron garnets. Growth of good quality single crystal garnet films containing as many as five different cations has been achieved over a wide range of deposition conditions. The relationship of film composition to alloy compositions and deposition conditions has been determined for several materials. By proper choice of the alloy composition and the deposition conditions, uncrazed deposits were grown on (111) gadolinium gallium garnet (GGG) substrates. Data on physical, magnetic and optical properties of representative films is presented and discussed.

Besser, P. J.; Hamilton, T. N.; Mee, J. E.; Stermer, R. L.

1974-01-01

232

Antibacterial effect of gallium and silver on Pseudomonas aeruginosa treated with gallium-silver-phosphate-based glasses.  

PubMed

Gallium and silver incorporated phosphate-based glasses were evaluated for antibacterial effect on the growth of Pseudomonas aeruginosa, which is a leading cause of opportunistic infections. The glasses were produced by conventional melt quenching methods at 1100°C for 1 h. Glass degradation studies were conducted by weight loss method. Disc diffusion assay and cell viability assay displayed statistically significant (p ? 0.0005) effect on P. aeruginosa growth which increased with decreasing calcium content in the glasses. The gallium ion release rates (1.83, 0.69 and 0.48 ppm·h(-1)) and silver ion release rates (2.97, 2.84 and 2.47 ppm·h(-1)) were found to account for this variation. Constant depth film fermentor was used to evaluate the anti-biofilm properties of the glasses. Both gallium and silver in the glass contributed to biofilm growth inhibitory effect on P. aeruginosa (up to 2.68 reduction in log?10 values of the viable counts compared with controls). The glasses were found to deliver gallium and silver in a controlled way and exerted cumulative antibacterial action on planktonic and biofilm growth of P. aeruginosa. The antibacterial, especially anti-biofilm, properties of the gallium and silver incorporated phosphate-based glasses make them a potential candidate to combat infections caused by P. aeruginosa. PMID:24840197

Valappil, Sabeel P; Higham, Susan M

2014-01-01

233

Magnetic field rotation in the screw gallium flow  

NASA Astrophysics Data System (ADS)

The magnetic field induced by the nonstationary screw flow of gallium in a toroidal channel has been investigated experimentally using a gallium prototype of the sodium apparatus developed in the frame of the experimental dynamo program at the Institute of Continuous Media Mechanics, Perm, Russia. The experimental set-up is a rapidly rotating toroidal channel subjected to abrupt braking. The screw flow is initiated by inertial forces pushing liquid gallium through diverters. The regular structure of the induced magnetic field is generated about 0.1 s after the stop of the channel and persists up to 1 s. The induced field is measured by sensors placed outside the channel. The inductive effects observed are attributed to the mean screw flow. The decay laws of the induced regular magnetic field and turbulent magnetic fluctuations are studied.

Noskov, V.; Denisov, S.; Frick, P.; Khripchenko, S.; Sokoloff, D.; Stepanov, R.

2004-10-01

234

The Soviet-American gallium experiment at Baksan  

SciTech Connect

A gallium solar neutrino detector is sensitive to the full range of the solar neutrino spectrum, including the low-energy neutrinos from the fundamental proton-proton fusion reaction. If neutrino oscillations in the solar interior are responsible for the suppressed {sup 8}B flux measured by the Homestake {sup 37}Cl experiment and the Kamiokande water Cherenkov detector, then a comparison of the gallium, chlorine, and water results may make possible a determination of the neutrino mass difference and mixing angle. A 30-ton gallium detector is currently operating in the Baksan laboratory in the Soviet Union, with a ratio of expected solar signal to measured background (during the first one to two {sup 71}Ge half lives) of approximately one. 28 refs.

Abazov, A. I.; Abdurashitov, D. N.; Anosov, O. L.; Danshin, S. N.; Eroshkina, L. A.; Faizov, E. L.; Gavrin, V. N.; Kalikhov, A. V.; Knodel, T. V.; Knyshenko, I. I.; Kornoukhov, V. N.; Mezentseva, S. A.; Mirmov, I. N.; Ostrinsky, A. I.; Petukhov, V. V; Pshukov, A. M.; Revzin, N. Ye; Shikhin, A. A.; Slyusareva, Ye. D.; Timofeyev, P. V.; Veretenkin, E. P.; Vermul, V. M.; Yantz, V. E.; Zakharov, Yu.; Zatsepin, G. T.; Zhandarov, V. I. [AN SSSR, Mosco

1990-01-01

235

Effect of bronchoscopy on localization of gallium-67 citrate  

SciTech Connect

Bronchoscopy, bronchoalveolar lavage (BAL), and 67Ga lung scans are frequently performed for diagnosis or follow-up of patients with sarcoidosis, interstitial pneumonitis, lymphoma, infections, and bronchogenic carcinoma. Because many patients undergo all 3 of these procedures, it is important to determine what effects bronchoscopy and/or BAL may have on gallium imaging. Because 67Ga accumulates in neutrophils at the site of an inflammatory lesion as well as in those circulating in the vascular compartment, it seems reasonable to postulate that bronchoscopy could cause migration of labeled neutrophils into the lung, resulting in false positive gallium scans. To test this hypothesis, we studied 5 patients with varying chronologic relationships of 67Ga injection, gallium scanning, and bronchoscopy with BAL. In all patients, the repeat 67Ga lung scans remained normal or showed no change after bronchoscopy and BAL. We conclude that bronchoscopy with or without BAL does not cause increased 67Ga uptake by the lung.

Phillips, B.A.; Cooper, K.R.; Fratkin, M.J.

1983-03-01

236

Dipeptide-assisted growth of uniform gallium oxohydroxide spindles  

NASA Astrophysics Data System (ADS)

The catalytic dipeptide His-Ser was used as an additive in mineralizing gallium ions to form GaOOH, a solid precursor of Ga 2O 3. This dipeptide was chosen to mimic the enzyme structure of silicatein, similar to the well-known catalytic triad of chymotrypsin. The dipeptide promoted formation of spindle-structured GaOOH under acidic conditions by behaving as a heterogeneous nucleation seed. In contrast, no well-defined, structured gallium species were produced in the absence of dipeptide. The catalytic function of the dipeptide was most pronounced at pH values in the range 3-5, which are lower than the pKa of imidazole in the His side chain. These results suggest that the catalytic role of dipeptide influences the gallium hydroxide conversion and growth. This study suggests that a designed peptide with active functionality can be further exploited to produce inorganic compounds with controlled nucleation and growth.

Lee, Inho; Kwak, Jinyoung; Haam, Seungjoo; Lee, Sang-Yup

2010-07-01

237

Extremely-efficient, miniaturized, long-lived alpha-voltaic power source using liquid gallium  

NASA Technical Reports Server (NTRS)

A power source converts .alpha.-particle energy to electricity for use in electrical systems. Liquid gallium or other liquid medium is subjected to .alpha.-particle emissions. Electrons are freed by collision from neutral gallium atoms to provide gallium ions. The electrons migrate to a cathode while the gallium ions migrate to an anode. A current and/or voltage difference then arises between the cathode and anode because of the work function difference of the cathode and anode. Gallium atoms are regenerated by the receiving of electrons from the anode enabling the generation of additional electrons from additional .alpha.-particle collisions.

Snyder, G. Jeffrey (Inventor); Patel, Jagdishbhai (Inventor); Fleurial, Jean-Pierre (Inventor)

2004-01-01

238

Electronic transitions in the bandgap of copper indium gallium diselenide polycrystalline thin films  

NASA Astrophysics Data System (ADS)

The electronic properties of polycrystalline copper indium gallium diselenide thin films have been investigated, with emphasis on understanding the distribution and origin of electronic states in the bandgap. The samples studied were working photovoltaic devices with the structure ZnO/CdS/CuIn1-xGa xSe2/Mo, and photovoltaic efficiencies ranging from 8 to 16%. The CdS layer and the p-type CuIn1-xGa xSe2 film create the n+- p junction at the heart of these devices. The samples were investigated using four techniques based on the electrical response of the junction: admittance spectroscopy, drive level capacitance profiling, transient photocapacitance spectroscopy, and transient photocurrent spectroscopy. From these measurements the free carrier densities, defect densities within the bandgap, spatial uniformity, and minority carrier mobilities have been deduced. The sub-bandgap response from the CuIn1-xGaxSe2 film was dominated by two defects. One exhibited a thermal transition to the valence band with an activation energy ranging between 0.1 and 0.3 eV and thermal emission prefactors obeying the Meyer-Neldel rule. The second was detected as an optical transition 0.8 eV from the valence band edge. Neither of these defects exhibited densities that varied systematically with gallium content, implying that they are not directly connected with the group III elements in these alloys. The defect densities also do not clearly correlate with the photovoltaic device performance; however, the position of the 0.8 eV defect lies nearer to mid-gap in the higher gallium, and hence higher band gap, material. This implies that it may be a more important recombination center in these devices and may be partially responsible for the reduced photovoltaic efficiencies observed when Ga/(In + Ga) > 0.4. An additional defect response was observed near mid-gap in films grown by processes known to produce lower quality devices. The influence of defects located at grain boundaries was also investigated by comparisons with a device based on an epitaxial single crystal CuIn1-xGa xSe2 film. The grain boundaries do not appear to contain significant quantities of additional defects with sub-bandgap electronic transitions. Finally, metastabilities in the defect distributions resulting from light exposure were also explored. Understanding these metastable changes is likely to lead to a better understanding of the role of the defects in the bandgap of CuIn1-xGaxSe2 films.

Heath, Jennifer Theresa

239

Mechanism of gallium-67 accumulation in inflammatory lesions  

SciTech Connect

Multiple factors contribute to the accumulation and retention of gallium-67 in inflammatory lesions. Adequate blood supply is essential. Gallium-67, mainly in the form of transferrin-Ga-67 complex, is delivered to the inflammatory lesions through capillaries with increased permeability. At the site of inflammation, some Ga-67 is taken up by leukocytes and bacteria when they are present. In addition, Ga-67 may also bind to lactoferrin and bacterial siderophores. Multiple contributing factors often coexist at any given inflammatory lesion. The nature and intensity of the inflammation affects the relative contribution of these factors.

Tsan, M.F.

1985-01-01

240

By Deborah A. Kramer No primary gallium was produced in the United States in consumption were adjusted to reflect full industry coverage.  

E-print Network

1 GALLIUM By Deborah A. Kramer No primary gallium was produced in the United States in consumption consumers of gallium in the world, its needs were met from imported material. France and Russia were the main sources for gallium imports. Almost all the gallium used in the United States

241

Gallium arsenide processing for gate array logic  

NASA Technical Reports Server (NTRS)

The development of a reliable and reproducible GaAs process was initiated for applications in gate array logic. Gallium Arsenide is an extremely important material for high speed electronic applications in both digital and analog circuits since its electron mobility is 3 to 5 times that of silicon, this allows for faster switching times for devices fabricated with it. Unfortunately GaAs is an extremely difficult material to process with respect to silicon and since it includes the arsenic component GaAs can be quite dangerous (toxic) especially during some heating steps. The first stage of the research was directed at developing a simple process to produce GaAs MESFETs. The MESFET (MEtal Semiconductor Field Effect Transistor) is the most useful, practical and simple active device which can be fabricated in GaAs. It utilizes an ohmic source and drain contact separated by a Schottky gate. The gate width is typically a few microns. Several process steps were required to produce a good working device including ion implantation, photolithography, thermal annealing, and metal deposition. A process was designed to reduce the total number of steps to a minimum so as to reduce possible errors. The first run produced no good devices. The problem occurred during an aluminum etch step while defining the gate contacts. It was found that the chemical etchant attacked the GaAs causing trenching and subsequent severing of the active gate region from the rest of the device. Thus all devices appeared as open circuits. This problem is being corrected and since it was the last step in the process correction should be successful. The second planned stage involves the circuit assembly of the discrete MESFETs into logic gates for test and analysis. Finally the third stage is to incorporate the designed process with the tested circuit in a layout that would produce the gate array as a GaAs integrated circuit.

Cole, Eric D.

1989-01-01

242

Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate  

PubMed Central

Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm2 using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si.

2014-01-01

243

Proton radiation and thermal stability of gallium nitride and gallium nitride devices  

NASA Astrophysics Data System (ADS)

In today's industry one can see a constant challenge to exceed the limits of yesterday's devices. For the last three decades, the III-V nitride semiconductors have been viewed as highly promising for semiconductor device applications. The primary focus of III-V nitrides, thus far, has been centered on light emitting diodes (LEDs), injection lasers for digital data reading and storage applications, and ultra violet photodetectors. Yet, another application is high-power electronic devices for space-borne communications systems. It is expected that GaN-based devices will be more resistant to radiation damage often encountered in space environments, though verification of this is just now being undertaken. In particular, no information is yet available about the sensitivity to radiation of devices using dielectrics such as MOSFETs. Similarly, very limited data has been reported on the effects of high-energy protons on GaN based devices of any type. For this reason the research presented in this dissertation was undertaken to study the radiation and thermal stability of gallium nitride materials and gallium nitride semiconductor diodes, with and without novel gate dielectrics such as, scandium oxide (Sc2O 3) and magnesium oxide (MgO) and the ternary mix of magnesium calcium oxide (MgCaO). It was found that though environmental degradation could be a problem for MgO dielectrics, the radiation exposure itself did not produce significant damage in either the Sc2O3, MgO or MgCaO dielectrics. Much of the minimal damage occurred in the GaN as shown by photoluminescence spectroscopy (PL).

Allums, Kimberly K.

244

The 100 micron detector development program. [gallium doped germanium photoconductors  

NASA Technical Reports Server (NTRS)

An effort to optimize gallium-doped germanium photoconductors (Ge:Ga) for use in space for sensitive detection of far infrared radiation in the 100 micron region is described as well as the development of cryogenic apparatus capable of calibrating detectors under low background conditions.

Moore, W. J.

1976-01-01

245

Discovery of gallium, germanium, lutetium, and hafnium isotopes  

SciTech Connect

Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Gross, J.L.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2012-09-15

246

Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes  

E-print Network

Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Gross, J L

2011-01-01

247

Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes  

E-print Network

Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

J. L. Gross; M. Thoennessen

2011-09-28

248

Gallium 67 imaging in monitoring lymphoma response to treatment  

Microsoft Academic Search

The value of gallium 67 (Ga) imaging in monitoring lymphoma response to treatment was assessed in 25 patients with Ga-avid tumors and compared to body computed tomography (CT), chest radiographs, and palpation of tumor infiltrated peripheral lymph nodes. Ga imaging was negative in 95% (20\\/21) of the patients who were clinically considered to be in remission and in whom treatment

Ora Israel; Dov Front; Menachem Lam; Simona Ben-Haim; Uriel Kleinhaus; Menachem Ben-Shachar; Eliezer Robinson; Gerald M. Kolodny

1988-01-01

249

Role of the gallium scan in Hodgkin's disease  

Microsoft Academic Search

The reports of 240 gallium scans on 165 patients with Hodgkin's disease were reviewed to compare results with higher doses with those in earlier studies that employed lower doses. Tracer concentrations in specific sites were correlated with radiologic and pathologic reports and with the clinical courses of the patients studied. There were no significant differences in overall results between newer

Fredrick B. Hagemeister; Susan M. Fesus; Lamk M. Lamki; Thomas P. Haynie

1990-01-01

250

Current role of gallium scanning in the management of lymphoma  

Microsoft Academic Search

Gallium 67 scanning in the malignant lympho mas has been done, with variable success, for over 20 years. After initial enthusiasm, the technique fell into disrepute and it was not until the early 1980s that it enjoyed a revival. There have been many major contributions to the literature, both favourable and unfavourable. The reasons for the latter include: poor instrumentation

Andrew F. McLaughlin; Michael A. Magee; Robert Greenough; Kevin C. Allman; Andrew E. Southee; Steven R. Meikle; Brian F. Hutton; Douglas E. Joshua; George J. Bautovich; John G. Morris

1990-01-01

251

Adsorption of primary substituted hydrocarbons onto solid gallium substrates.  

PubMed

Adsorption of a series of primary substituted hydrocarbons (RX; C18H37PO(OH)2 (ODPA), C17H35COOH, C18H37OH, C18H37NH2, and C18H37SH) onto solid gallium substrates with and without UV/ozone treatment was studied using contact angle goniometry, spectroscopic ellipsometry, and cyclic voltammetry (CV). UV/ozone treatment offered a hydrophilic surface (water contact angle (?(water)) less than 10°), reflecting the formation of a surface oxide layer with the maximum thickness of ca. 1 nm and possibly the removal of surface contaminants. Upon immersion in a toluene solution of a RX, ?(water) increased due to adsorption of the RX onto gallium substrates. In particular, UV/ozone-treated gallium substrates (UV-Ga) immersed in an ODPA solution exhibited ?(water) close to 105°. The ellipsometric thickness of the adsorbed ODPA layer was ca. 2.4 nm, and CV data measured in an acetonitrile solution showed significant inhibition of redox reaction on the substrate surface. These results indicate the formation of a densely packed ODPA monolayer on UV-Ga. The coverage of a C17H35COOH layer adsorbed onto UV-Ga was lower, as shown by smaller ?(water) (ca. 99°), smaller ellipsometric thickness (ca. 1.3 nm), and smaller electrode reaction inhibition. Adsorption of the other RX onto UV-Ga was weaker, as indicated by smaller ?(water) (82°-92°). ODPA did not strongly adsorb onto UV-untreated gallium substrates, suggesting that the ODPA adsorption mainly originates from hydrogen bond interaction of a phosphonate group with surface oxide. These results will provide a means for controlling the surface properties of oxide-coated gallium that play an essential role in monolayer conductivity measurements and electroanalytical applications. PMID:23484619

De Silva, Chrishani M; Pandey, Bipin; Li, Feng; Ito, Takashi

2013-04-01

252

Fluidic patch antenna based on liquid metal alloy/single-wall carbon-nanotubes operating at the S-band frequency  

E-print Network

., 151 Hymus Boulevard, Montreal H9R 1E9, Canada 2 Center for Applied Research on Polymers (CREPEC-band frequency (4GHz). The antenna prototype is composed of a nanocomposite material made by a liquid metal alloy (eutectic gallium indium) blended with single-wall carbon-nanotube (SWNTs). The nanocomposite

253

Self- and zinc diffusion in gallium antimonide  

SciTech Connect

The technological age has in large part been driven by the applications of semiconductors, and most notably by silicon. Our lives have been thoroughly changed by devices using the broad range of semiconductor technology developed over the past forty years. Much of the technological development has its foundation in research carried out on the different semiconductors whose properties can be exploited to make transistors, lasers, and many other devices. While the technological focus has largely been on silicon, many other semiconductor systems have applications in industry and offer formidable academic challenges. Diffusion studies belong to the most basic studies in semiconductors, important from both an application as well as research standpoint. Diffusion processes govern the junctions formed for device applications. As the device dimensions are decreased and the dopant concentrations increased, keeping pace with Moore's Law, a deeper understanding of diffusion is necessary to establish and maintain the sharp dopant profiles engineered for optimal device performance. From an academic viewpoint, diffusion in semiconductors allows for the study of point defects. Very few techniques exist which allow for the extraction of as much information of their properties. This study focuses on diffusion in the semiconductor gallium antimonide (GaSb). As will become clear, this compound semiconductor proves to be a powerful one for investigating both self- and foreign atom diffusion. While the results have direct applications for work on GaSb devices, the results should also be taken in the broader context of III-V semiconductors. Results here can be compared and contrasted to results in systems such as GaAs and even GaN, indicating trends within this common group of semiconductors. The results also have direct importance for ternary and quaternary semiconductor systems used in devices such as high speed InP/GaAsSb/InP double heterojunction bipolar transistors (DHBT) [Dvorak, (2001)]. Many of the findings which will be reported here were previously published in three journal articles. Hartmut Bracht was the lead author on two articles on self-diffusion studies in GaSb [Bracht, (2001), (2000)], while this report's author was the lead author on Zn diffusion results [Nicols, (2001)]. Much of the information contained herein can be found in those articles, but a more detailed treatment is presented here.

Nicols, Samuel Piers

2002-03-26

254

Heusler alloys  

Microsoft Academic Search

In 1903 F. Heusler reported that it was possible to make ferromagnetic alloys from non-ferromagnetic constituents copper-manganese bronze and group B elements such as aluminium and tin. Further investigations showed that the magnetic properties of these alloys are related to their chemical, L21, structure, and to the ordering of the manganese atoms on an f.c.c. sublattice.Heusler alloys are properly described

Peter J. Webster

1969-01-01

255

Corrosion of alloy 718 in a mercury thermal convection loop  

SciTech Connect

Two thermal convection loops (TCLs) fabricated from annealed alloy 718 continuously circulated mercury (Hg) with 1000 wppm gallium (Ga), respectively, for about 5000 h, duplicating previous TCL tests for annealed 316L. In each case, the maximum loop temperature was 305C, the minimum temperature was 242C, and the Hg flow rate was approximately 1.2 m/min. Unlike the 316L exposed to Hg, which above about 260C exhibited a thin, porous surface layer depleted in Ni and Cr, the alloy 718 coupons revealed essentially no wetting and, therefore, no interaction with that Hg at any temperature. Alloy 718 coupons suspended in the loops revealed inconsequentially small weight changes, and both the coupons and loop tubing exhibited no detectable metallographic evidence of attack.

Pawel, S.J.; DiStefano, J.R.; Manneschmidt, E.T.

1999-12-01

256

Brittle-to-ductile transition in polycrystalline aluminum containing gallium in the grain boundaries  

NASA Astrophysics Data System (ADS)

It is well known that aluminum/gallium couple causes liquid metal embrittlement. Gallium atoms penetrate the grain boundaries of polycrystalline aluminum and degrade it. Polycrystalline aluminum specimens were contacted with a small droplet of gallium for 24 h. After gallium was removed from the surface of the specimens, tensile tests were performed between 77 K and 313 K. The specimens are ductile below 230 K and brittle above 303 K, the melting temperature of gallium. Between 280 K and 300 K, the maximum stress is larger in the specimens heated from 77 K than in those cooled from 313 K. This thermal history dependence of the maximum stress is considered to be attributed to the solidification of supercooled gallium in the grain boundaries.

Itoh, A.; Izumi, J.; Ina, K.; Koizumi, H.

2010-07-01

257

Generalized stacking fault energies of alloys.  

PubMed

The generalized stacking fault energy (? surface) provides fundamental physics for understanding the plastic deformation mechanisms. Using the ab initio exact muffin-tin orbitals method in combination with the coherent potential approximation, we calculate the ? surface for the disordered Cu-Al, Cu-Zn, Cu-Ga, Cu-Ni, Pd-Ag and Pd-Au alloys. Studying the effect of segregation of the solute to the stacking fault planes shows that only the local chemical composition affects the ? surface. The calculated alloying trends are discussed using the electronic band structure of the base and distorted alloys.Based on our ? surface results, we demonstrate that the previous revealed 'universal scaling law' between the intrinsic energy barriers (IEBs) is well obeyed in random solid solutions. This greatly simplifies the calculations of the twinning measure parameters or the critical twinning stress. Adopting two twinnability measure parameters derived from the IEBs, we find that in binary Cu alloys, Al, Zn and Ga increase the twinnability, while Ni decreases it. Aluminum and gallium yield similar effects on the twinnability. PMID:24903220

Li, Wei; Lu, Song; Hu, Qing-Miao; Kwon, Se Kyun; Johansson, Börje; Vitos, Levente

2014-07-01

258

Gallium uptake in the thyroid gland in amiodarone-induced hyperthyroidism  

SciTech Connect

Amiodarone is an iodinated antiarrhythmic agent that is effective in the treatment of atrial and ventricular arrhythmias. A number of side effects are seen, including pulmonary toxicity and thyroid dysfunction. A patient with both amiodarone-induced pneumonitis and hyperthyroidism who exhibited abnormal gallium activity in the lungs, as well as diffuse gallium uptake in the thyroid gland is presented. The latter has not been previously reported and supports the concept of iodide-induced thyroiditis with gallium uptake reflecting the inflammatory response.

Ling, M.C.; Dake, M.D.; Okerlund, M.D.

1988-04-01

259

THE PREPARATION AND STUDY OF THE OPTICAL ABSORPTION EDGE OF THIN FILMS OF GALLIUM ARSENIDE  

E-print Network

212. THE PREPARATION AND STUDY OF THE OPTICAL ABSORPTION EDGE OF THIN FILMS OF GALLIUM ARSENIDE Par gallium par évaporation sur des supports amorphes. On décrit une méthode simple et efficace pour évaporer l'arséniure de gallium, méthode qui pourrait être applicable à d'autres composes III-V. On a trouvé

Boyer, Edmond

260

CONTRLE DU DOPAGE DANS LA CROISSANCE PITAXIALE D'ARSNIURE DE GALLIUM  

E-print Network

5 CONTR�LE DU DOPAGE DANS LA CROISSANCE �PITAXIALE D'ARS�NIURE DE GALLIUM A. BOUCHER, J. P. CHAN� profil de dopage de couches d'arséniure de gallium préparées par épitaxie en phase vapeur. Nous décrivons of vapor grown Gallium Arsenide epitaxial layers. An operating process of doping by back-diffusion and our

Paris-Sud XI, Université de

261

Critical Fields and Growth Rates of the Tayler Instability as Probed by a Columnar Gallium Experiment  

NASA Astrophysics Data System (ADS)

Many astrophysical phenomena (such as the slow rotation of neutron stars or the rigid rotation of the solar core) can be explained by the action of the Tayler instability of toroidal magnetic fields in the radiative zones of stars. In order to place the theory of this instability on a safe fundament, it has been realized in a laboratory experiment measuring the critical field strength, the growth rates, as well as the shape of the supercritical modes. A strong electrical current flows through a liquid metal confined in a resting columnar container with an insulating outer cylinder. As the very small magnetic Prandtl number of the gallium-indium-tin alloy does not influence the critical Hartmann number of the field amplitudes, the electric currents for marginal instability can also be computed with direct numerical simulations. The results of this theoretical concept are confirmed by the experiment. Also the predicted growth rates on the order of minutes for the nonaxisymmetric perturbations are certified by the measurements. That they do not directly depend on the size of the experiment is shown as a consequence of the weakness of the applied fields and the absence of rotation.

Rüdiger, Günther; Gellert, Marcus; Schultz, Manfred; Strassmeier, Klaus G.; Stefani, Frank; Gundrum, Thomas; Seilmayer, Martin; Gerbeth, Gunter

2012-08-01

262

Nonpolar m-plane gallium Nitride-based Laser Diodes in the Blue Spectrum  

NASA Astrophysics Data System (ADS)

Gallium nitride (GaN), together with its alloys with aluminum and indium, have revolutionized the solid-state optoelectronics market for their ability to emit a large portion of the visible electromagnetic spectrum from deep ultraviolet and into the infrared. GaN-based semiconductor laser diodes (LDs) with emission wavelengths in the violet, blue and green are already seeing widespread implementation in applications ranging from energy storage, lighting and displays. However, commercial GaN-based LDs use the basal c-plane orientation of the wurtzite crystal, which can suffer from large internal electric fields due to discontinuities in spontaneous and piezoelectric polarizations, limiting device performance. The nonpolar orientation of GaN benefits from the lack of polarization-induced electric field as well as enhanced gain. This dissertation discusses some of the benefits and limitations of m-plane oriented nonpolar GaN for LD applications in the true blue spectrum (450 nm). Topics include an overview of material growth by metal-organic chemical vapor deposition (MOCVD), waveguide design and processing techniques for improving device performance for multiple lateral mode and single lateral mode ridge waveguides.

Kelchner, Kathryn M.

263

Cutaneous gallium uptake in patients with AIDS with mycobacterium avium-intracellulare septicemia  

SciTech Connect

Gallium imaging is increasingly being used for the early detection of complications in patients with AIDS. A 26-year-old homosexual man who was HIV antibody positive underwent gallium imaging for investigation of possible Pneumocystis carinii pneumonia. Widespread cutaneous focal uptake was seen, which was subsequently shown to be due to mycobacterium avium-intracellulare (MAI) septicemia. This case demonstrates the importance of whole body imaging rather than imaging target areas only, the utility of gallium imaging in aiding the early detection of clinically unsuspected disease, and shows a new pattern of gallium uptake in disseminated MAI infection.

Allwright, S.J.; Chapman, P.R.; Antico, V.F.; Gruenewald, S.M.

1988-07-01

264

Neutron detection using boron gallium nitride semiconductor material  

SciTech Connect

In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN) semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN) samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to ?-rays but poor sensitivity to ?-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in a neutron-detection signal after ?-rays were generated by the capture of neutrons by the B atoms. These results prove that BGaN is useful as a neutron-detecting semiconductor material.

Atsumi, Katsuhiro [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Inoue, Yoku; Nakano, Takayuki, E-mail: ttnakan@ipc.shizuoka.ac.jp [Department of Electrical and Materials Science, Graduate School of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Mimura, Hidenori; Aoki, Toru [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8011 (Japan)

2014-03-01

265

Gallium nitride nanowires by maskless hot phosphoric wet etching  

NASA Astrophysics Data System (ADS)

We demonstrate gallium nitride (GaN) nanowires formation by controlling the selective and anisotropic etching of N-polar GaN in hot phosphoric acid. Nanowires of ˜109/cm,2 total height of ˜400 nm, and diameters of 170-200 nm were obtained. These nanowires have both non-polar {11¯00}/ {112¯0} and semi-polar {1011¯} facets. X-Ray Diffraction characterization shows that screw dislocations are primarily responsible for preferential etching to create nanowires. Indium gallium nitride multi-quantum wells (MQWs) grown on these GaN nanowires showed a blue shift in peak emission wavelength of photoluminescence spectra, and full width at half maximum decreased relative to MQWs grown on planar N-polar GaN, respectively.

Bharrat, D.; Hosalli, A. M.; Van Den Broeck, D. M.; Samberg, J. P.; Bedair, S. M.; El-Masry, N. A.

2013-08-01

266

Gallium nitride films made by liquid target pulsed laser deposition  

NASA Astrophysics Data System (ADS)

In this paper, formation of single c-axis oriented wurtzite gallium nitride films on various substrates as fused silica, Si and sapphire with ZnO buffer layers by liquid target pulsed laser deposition is reported. The deposition conditions were optimized with a temperature of 600 degrees C and an ammonia pressure of 750mTorr. X-ray diffraction, scanning electron microscopy, tunneling electron microscopy, room temperature Hall effect measurement, UV/VIS spectrometry, Rutherford backscattering spectroscopy and x- ray photoelectron spectroscopy were used to characterize the as-grown films. It is shown that high quality single c-axis orientation stoichiometric gallium nitride films could be formed with a thin zinc oxide buffer layer. The FWHM of x- ray rocking curve of the peak of GaN grown on ZnO/sapphire was as narrow as 0.52 degrees. It was also found that the surface morphology was greatly improved with the zinc oxide buffer.

Sun, X. W.; Xiao, Rongfu; Kwok, HoiSing

1996-09-01

267

Aging and memory effect in magnetoelectric gallium ferrite single crystals  

NASA Astrophysics Data System (ADS)

Here, we present a time and temperature dependent magnetization study to understand the spin dynamics in flux grown single crystals of gallium ferrite (GaFeO3), a known magnetoelectric, ferroelectric and ferrimagnet. Results of the magnetic measurements conducted in the field-cooled (FC) and zero-field-cooled (ZFC) protocols in the heating and cooling cycles were reminiscent of a "memory" effect. Subsequent time dependent magnetic relaxation measurements carried out in ZFC mode at 30 K with an intermittent cooling to 20 K in the presence of a small field show that the magnetization in the final wait period tends to follow its initial state which was present before the cooling break taken at 20 K. These observations provide an unambiguous evidence of single crystal gallium ferrite having a spin glass like phase.

Singh, Vijay; Mukherjee, Somdutta; Mitra, Chiranjib; Garg, Ashish; Gupta, Rajeev

2015-02-01

268

Process for oxidizing semiconducting compounds, especially gallium arsenide  

SciTech Connect

In order to provide a semiconductive substrate such as gallium arsenide with an oxide layer, the substrate is positively biased in a plasma reactor in which an oxidizing gas is ionized by radiofrequency excitation while the substrate is heated to an elevated temperature increasing its conductivity. The substrate may be placed for this purpose on a graphite pedestal which is inductively heated from the same radiofrequency source.

Centronio, A.

1984-02-21

269

Three-dimensional free convection in molten gallium  

Microsoft Academic Search

Convective flow of molten gallium is studied in a small-aspect-ratio rectangular, differentially heated enclosure. The three-dimensional nature of the steady flow is clearly demonstrated by quantitative comparison between experimental temperature measurements, which give an indication of the strength of the convective flow, and the results of numerical simulations. The three-dimensional flow structure is characterized by cross-flows which are an order

A. Juel; T. Mullin; H. Ben Hadid; D. Henry

2001-01-01

270

Gallium transformation under femtosecond laser excitation: Phase coexistenceand incomplete melting  

NASA Astrophysics Data System (ADS)

The reversible phase transition induced by femtosecond laser excitation of Gallium has been studied by measuring the dielectric function at 775nm with ˜200fs temporal resolution. The real and imaginary parts of the transient dielectric function were calculated using the Fresnel formulae from the absolute reflectivity of a Gallium layer measured at two different angles of incidence. The time-dependent effective electron-phonon collision frequency; the heat conduction coefficient; and the volume fraction of the new phase were recovered directly from the experimental data. The time and space dependent electron and lattice temperatures in the layer undergoing the phase transition were reconstructed without ad hoc assumptions. We converted the temporal dependence of the electron-phonon collision rate into its temperature dependence, and demonstrated that the electron-phonon collision rate has a nonlinear character. This temperature dependence converges to the known equilibrium function during the cooling stage. The maximum fraction of the new phase in the laser-excited Gallium layer reached only 60% even when the deposited energy was twice the equilibrium enthalpy of melting. We demonstrate that the rate at which the phase transition proceeds and a fraction of the material transformed into the new phase depends strongly on the temperature of the laser-excited Gallium layer, and is restricted by the thickness of this layer which is only several tens of nanometers for the whole range of the pump laser fluences. The kinetics of the phase transformation after the laser excitation can be understood on the basis of the classical theory of the first-order phase transition.

Uteza, O. P.; Gamaly, E. G.; Rode, A. V.; Samoc, M.; Luther-Davies, B.

2004-08-01

271

Radiation damage of gallium arsenide induced by reactive ion etching  

Microsoft Academic Search

Radiation damage induced in the surface of gallium arsenide (GaAs) by reactive ion etching (RIE)is studied using physical and electrical analyses. The number of displaced Ga and As atoms observed by Rutherford backscattering spectrometry aligned spectra is 7.8×1015 cm?2 and 1.3×1016 cm?2 at rf power of 300 W (0.47 W\\/cm2) and 500 W (0.78 W\\/cm2), respectively. The barrier height of

Tohru Hara; Hidenori Suzuki; Akio Suga; Toshiyuki Terada; Nobuyuki Toyoda

1987-01-01

272

Terahertz Cherenkov radiation from ultrafast magnetization in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

We report an experimental observation of terahertz Cherenkov radiation from a moving magnetic moment produced in terbium gallium garnet by a circularly polarized femtosecond laser pulse via the inverse Faraday effect. Contrary to some existing theoretical predictions, the polarity of the observed radiation unambiguously demonstrates the paramagnetic, rather than diamagnetic, nature of the ultrafast inverse Faraday effect. From measurements of the radiation field, the Verdet constant in the subpicosecond regime is ˜3-10 times smaller than its table quasistatic value.

Gorelov, S. D.; Mashkovich, E. A.; Tsarev, M. V.; Bakunov, M. I.

2013-12-01

273

Gallium67 citrate imaging for the assessment of radiation pneumonitis  

Microsoft Academic Search

In order to evaluate its usefulness in the assessment of radiation pneumonitis, gallium-67 citrate (67Ga) imaging was performed before and after radiation therapy (RT) on 103 patients with lung cancer. In 23 patients with radiation\\u000a pneumonitis detected radiographically, abnormal67Ga uptake in sites other than tumors was found in all post-RT67Ga lung images. Three patterns of uptake were found: (A), focal

Masaaki Kataoka

1989-01-01

274

A gallium phosphide high-temperature bipolar junction transistor  

Microsoft Academic Search

Preliminary results are reported on the development of a high-temperature (> 350°C) gallium phosphide bipolar junction transistor (BJT) for goethermal and other energy applications. This four-layer p\\/sup +\\/n⁻pp\\/sup +\\/ structure was fromed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into

T. E. Zipperian; L. R. Dawson; R. J. Caffin

1981-01-01

275

Ultra-wideband source using gallium arsenide photoconductive semiconductor switches  

Microsoft Academic Search

An ultrawide-band (UWB) pulse generator based on high-gain (lock-on mode) gallium arsenide (GaAs) photoconductive semiconductor switches (PCSS's) is presented. Revised PCSS contact design shows improved performance in hold-off field, on-state switch potential, and switching jitter, while reducing the switch volume by 75% compared to previous designs. A compact laser diode module operates at 904 nm and triggers the PCSS at

Jon S. H. Schoenberg; Jeffrey W. Burger; J. Scott Tyo; Michael D. Abdalla; Michael C. Skipper; Walter R. Buchwald

1997-01-01

276

Mechanisms of localization of gallium-67 in tumors  

Microsoft Academic Search

The mechanism of tumor localization of gallium-67 (⁶⁷Ga) is not known with certainty, although much information has been derived regarding the biodistribution and subcellular fate of ⁶⁷Ga in a variety of tumors and other tissues from experimental animals. After intravenous administration, ⁶⁷Ga is bound to transferrin in the blood, and distributed to liver, lacrimal glands, salivary glands, and soft tissue

S LARSON

1978-01-01

277

POLLUTION PREVENTION IN THE SEMICONDUCTOR INDUSTRY THROUGH RECOVERY AND RECYCLING OF GALLIUM AND ARSENIC FROM GAAS POLISHING WASTES  

EPA Science Inventory

A process was developed for the recovery of both arsenic and gallium from gallium arsenide polishing wastes. The economics associated with the current disposal techniques utilizing ferric hydroxide precipitation dictate that sequential recovery of toxic arsenic and valuble galliu...

278

Polarized Raman Confocal Microscopy of Single Gallium Nitride Nanowires Peter J. Pauzauskie, David Talaga, Kwanyong Seo,, Peidong Yang,*, and  

E-print Network

Polarized Raman Confocal Microscopy of Single Gallium Nitride Nanowires Peter J. Pauzauskie, David semiconductor gallium nitride (GaN) are prime candidates for future nanoscale devices such as short wavelength

Yang, Peidong

279

Influence of Ligand Rigidity and Ring Substitution on the Structural and Electronic Behavior of Trivalent Iron and Gallium Complexes with  

E-print Network

of Trivalent Iron and Gallium Complexes with Asymmetric Tridentate Ligands Camille Imbert, Hrant P. Hratchian) and d10 gallium (5, 6) were synthesized and characterized to assess the influence of the ligand rigidity

Schlegel, H. Bernhard

280

Appraisal of lupus nephritis by renal imaging with gallium-67  

SciTech Connect

To assess the activity of lupus nephritis, 43 patients with systemic lupus erythematosus (SLE) were studied by gallium imaging. Delayed renal visualization 48 hours after the gallium injection, a positive result, was noted in 25 of 48 scans. Active renal disease was defined by the presence of hematuria, pyuria (10 or more red blood cells or white blood cells per high-power field), proteinuria (1 g or more per 24 hours), a rising serum creatinine level, or a recent biopsy specimen showing proliferative and/or necrotizing lesions involving more than 20 percent of glomeruli. Renal disease was active in 18 instances, inactive in 23, and undetermined in seven (a total of 48 scans). Sixteen of the 18 scans (89 percent) in patients with active renal disease showed positive findings, as compared with only four of 23 scans (17 percent) in patients with inactive renal disease (p less than 0.001). Patients with positive scanning results had a higher rate of hypertension (p = 0.02), nephrotic proteinuria (p = 0.01), and progressive renal failure (p = 0.02). Mild mesangial nephritis (World Health Organization classes I and II) was noted only in the patients with negative scanning results (p = 0.02) who, however, showed a higher incidence of severe extrarenal SLE (p = 0.04). It is concluded that gallium imaging is a useful tool in evaluating the activity of lupus nephritis.

Bakir, A.A.; Lopez-Majano, V.; Hryhorczuk, D.O.; Rhee, H.L.; Dunea, G.

1985-08-01

281

Incidental diagnosis of pregnancy on bone and gallium scintigraphy  

SciTech Connect

Bone and gallium scintigraphy were performed as part of the diagnostic workup of a 21-yr-old woman who presented at our institution with a history of progressively worsening low back pain over a 1-wk period of time. The angiographic phase of the bone scan demonstrated a well-defined radionuclide blush within the pelvis just cephalad to the urinary bladder with persistent hyperemia noted in the blood-pool image. We attribute these findings to a uterine blush secondary to the pronounced uterine muscular hyperplasia, hyperemia, and edema that accompany pregnancy. Gallium scintigraphy demonstrated intense bilateral breast accumulation of the imaging agent in a typical doughnut pattern which is commonly found in the prelactating and lactating breast. Also demonstrated was apparent gallium accumulation in the placenta. This case is presented to emphasize the radionuclide findings that occur during pregnancy, particularly the incidental finding of radionuclide blush during the angiographic phase of a radionuclide scintigraphy which should alert the nuclear physician to the possibility of pregnancy in a woman of childbearing age.

Palestro, C.J.; Malat, J.; Collica, C.J.; Richman, A.H.

1986-03-01

282

Atmospheric pressure chemical vapor deposition of gallium doped zinc oxide thin films from diethyl zinc, water, and triethyl gallium  

NASA Astrophysics Data System (ADS)

Gallium doped zinc oxide films have been deposited in the temperature range 150 to 470 C from 0.05 percent diethyl zinc, 0.8 percent water, and various triethyl gallium concentrations. The films are polycrystalline with crystallite sizes varying between 275 and 500 A for undoped films and between 125 and 400 A for doped films. Only those films deposited above 430 C are highly oriented and have their c axes perpendicular to the substrate plane. The electron density, conductivity, and mobility always increase with temperature. Thicker films have higher conductivity and mobility than thinner films. The refractive index is reduced from 1.96 to 1.73 when the electron density is increased from zero to 3.7 x 10 exp 20/cu cm.

Hu, Jianhua; Gordon, Roy G.

1992-12-01

283

Electronic Structure of Magnetic Impurities in III-V Semiconductors: Mn and Fe in Gallium Nitride and Gallium Antimony  

NASA Astrophysics Data System (ADS)

Mn and Fe impurities in zinc-blende gallium nitride (GaN) and gallium antimony (GaSb) are investigated by the LMTO-TB method. The calculations use a 128-site supercell with Mn and Fe atoms replacing ions at cation and anion sublattices, respectively. Both Mn and Fe appear to be magnetic for all types of substitutions. The magnetic moment for each case will be given. The moments are highly localized, and some weak polarization for the first neighbor atoms is obtained. The total energies for the supercell with and without magnetic impurities are used to determine the most probable substitutional sites for doping Mn and Fe in GaN and GaSb. The energies of the magnetic impurity levels relative to the edges of the valence and conduction bands of the host crystal are analyzed by using the total and partial densities of states. The calculated results are compared with available experimental data.

Gubanov, Vladimir A.; Boekema, C.

1998-03-01

284

Smooth cubic commensurate oxides on gallium nitride  

SciTech Connect

Smooth, commensurate alloys of ?111?-oriented Mg{sub 0.52}Ca{sub 0.48}O (MCO) thin films are demonstrated on Ga-polar, c+ [0001]-oriented GaN by surfactant-assisted molecular beam epitaxy and pulsed laser deposition. These are unique examples of coherent cubic oxide|nitride interfaces with structural and morphological perfection. Metal-insulator-semiconductor capacitor structures were fabricated on n-type GaN. A comparison of leakage current density for conventional and surfactant-assisted growth reveals a nearly 100× reduction in leakage current density for the surfactant-assisted samples. HAADF-STEM images of the MCO|GaN interface show commensurate alignment of atomic planes with minimal defects due to lattice mismatch. STEM and DFT calculations show that GaN c/2 steps create incoherent boundaries in MCO over layers which manifest as two in-plane rotations and determine consequently the density of structural defects in otherwise coherent MCO. This new understanding of interfacial steps between HCP and FCC crystals identifies the steps needed to create globally defect-free heterostructures.

Paisley, Elizabeth A.; Gaddy, Benjamin E.; LeBeau, James M.; Shelton, Christopher T.; Losego, Mark D.; Mita, Seiji; Collazo, Ramón; Sitar, Zlatko; Irving, Douglas L.; Maria, Jon-Paul, E-mail: jpmaria@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Biegalski, Michael D.; Christen, Hans M. [Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2014-02-14

285

Gallium phosphide as a new material for anodically bonded atomic sensors Nezih Dural and Michael V. Romalis  

E-print Network

Gallium phosphide as a new material for anodically bonded atomic sensors Nezih Dural and Michael V); 10.1063/1.3638129 Nitrogen-polar gallium nitride substrates as solid-state p H -selective. 87, 093506 (2005); 10.1063/1.2037201 A model for pore growth in anodically etched gallium phosphide J

Romalis, Mike

286

Thermal and nonthermal melting of gallium arsenide after femtosecond laser excitation K. Sokolowski-Tinten, J. Bialkowski, and M. Boing  

E-print Network

Thermal and nonthermal melting of gallium arsenide after femtosecond laser excitation K. Sokolowski Received 19 March 1998; revised manuscript received 6 July 1998 Thermal- and nonthermal melting in gallium extensively studied during the past decade. Time resolved optical experiments on silicon,1­3 gallium arsenide

von der Linde, D.

287

CHANGEMENTS DE PHASE DU GALLIUM A LA PRESSION ATMOSPHRIQUE Par L. BOSIO, A. DEFRAIN et I. EPELBOIN,  

E-print Network

61. CHANGEMENTS DE PHASE DU GALLIUM A LA PRESSION ATMOSPH�RIQUE Par L. BOSIO, A. DEFRAIN et I faible volume dans l'étude de la germination dans le gallium liquide, on montre que les conditions de la of the choice of small volume samples in the study of nucleation in liquid gallium, the authors show

Paris-Sud XI, Université de

288

Gallium oxide and dioxide: Investigation of the ground and low-lying electronic states via anion photoelectron spectroscopy  

E-print Network

Gallium oxide and dioxide: Investigation of the ground and low-lying electronic states via anion nanostructures can be built. Gallium oxide, Ga2O3, is a candidate material for nanostructures because of its attrac- tive bulk properties such as luminescence1 and conduction.2 Gallium oxide nanowires,3 nanosheets

Neumark, Daniel M.

289

Histidine pKa shifts and changes of tautomeric states induced by the binding of gallium-protoporphyrin IX  

E-print Network

Histidine pKa shifts and changes of tautomeric states induced by the binding of gallium were studied in both apo- and holo-forms of HasASM in solution. Holo-HasASM was formed with gallium; hemophore; gallium; protoporphyrin Bacteria have developed various mechanisms for scaveng- ing iron, thus

Paris-Sud XI, Université de

290

Synthesis and microstructure of gallium phosphide nanowires W. S. Shi, Y. F. Zheng, N. Wang,a)  

E-print Network

Synthesis and microstructure of gallium phosphide nanowires W. S. Shi, Y. F. Zheng, N. Wang,a) C. S May 2001 Gallium phosphide GaP nanowires of 22 nm in diameter and hundreds micrometers in length were synthesized by laser ablation of a powder mixture of GaP and gallium oxide (Ga2O3 . The morphology

Zheng, Yufeng

291

Saturated Buffer FET Logic for Gallium Arsenide Digital Circuits A.E. Parker & D.J. Skellern.  

E-print Network

Saturated Buffer FET Logic for Gallium Arsenide Digital Circuits A.E. Parker & D.J. Skellern Logic (SBFL) is a new logic family developed for use in Gallium Arsenide digital integrated circuits) inverter circuit is shown in figure 1. This circuit is designed for use in Gallium Arsenide digital

292

Journal of Engineering Physics and Thermophysics, VoL 71, No..5, 1998 SIMULATION OF A GALLIUM ARSENIDE RUNNING  

E-print Network

Journal of Engineering Physics and Thermophysics, VoL 71, No..5, 1998 SIMULATION OF A GALLIUM, and V. A. Sizyuk UDC 621.382 Process of transfer of electrons in a gallium arsenide running. Such structures in the most cases are planar wave-conducting devices on gallium arsenide with a decelerating

Harilal, S. S.

293

SiliconPV: 17-20 April 2011, Freiburg, Germany Electrical properties of boron, phosphorus and gallium  

E-print Network

and gallium co-doped silicon Erwann Fourmonda , Maxime Forstera,b , Roland Einhausb , Hubert Lauvrayb , Jed from solar grade poly Silicon, to which Boron, Phosphorous and Gallium were added as dopants. The introduction of Gallium as a third dopant allowed for a better control of the resistivity and the doping type

Paris-Sud XI, Université de

294

Synthesis and use of (polyfluoroaryl)fluoroanions of aluminum, gallium and indium  

DOEpatents

Salts of (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are described. The (polyfluoroaryl)fluoroanions have the formula [ER'R"R'"F].sup..crclbar. wherein E is aluminum, gallium, or indium, wherein F is fluorine, and wherein R', R", and R'" is each a fluorinated phenyl, fluorinated biphenyl, or fluorinated polycyclic group.

Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

2000-01-01

295

Gas Source Molecular Beam Epitaxy of Aluminum Gallium Indium Phosphide for Visible Spectrum Light Emitting Diodes  

Microsoft Academic Search

Gas source molecular beam epitaxy is an advanced crystal growth technique that has been shown to be capable of producing high quality, ultra-thin semiconductor layers and interfaces, excellent dopant and thickness uniformity, and precisely controlled compositions in the aluminum gallium indium arsenide and indium phosphide material systems. This work extends this growth technique to the aluminum gallium indium phosphide material

James Nelson Baillargeon

1991-01-01

296

NON-SELECTIVE OXIDATION OF ALUMINUM GALLIUM ARSENIDE HETEROSTRUCTURES FOR HIGH PERFORMANCE CURVED WAVEGUIDE  

E-print Network

NON-SELECTIVE OXIDATION OF ALUMINUM GALLIUM ARSENIDE HETEROSTRUCTURES FOR HIGH PERFORMANCE CURVED;©Copyright 2008 Jusong Wang, B.S., M.S. #12;NON-SELECTIVE OXIDATION OF ALUMINUM GALLIUM ARSENIDE dry etching via reactive ion etching (RIE) to achieve a high index contrast (HIC) ridge waveguide (RWG

297

Two-photon photovoltaic effect in gallium arsenide Jeff Chiles,1  

E-print Network

Two-photon photovoltaic effect in gallium arsenide Jichi Ma,1 Jeff Chiles,1 Yagya D. Sharma,2 214669); published September 4, 2014 The two-photon photovoltaic effect is demonstrated in gallium; (230.0250) Optoelectronics; (040.5350) Photovoltaic; (130.4310) Nonlinear. http://dx.doi.org/10.1364/OL

Fathpour, Sasan

298

Low temperature recombination and trapping analysis in high purity gallium arsenide by microwave photodielectric techniques  

NASA Technical Reports Server (NTRS)

Some physical theories pertinent to the measurement properties of gallium arsenide are presented and experimental data are analyzed. A model for explaining recombination and trapping high purity gallium arsenide, valid below 77 K is assembled from points made at various places and an appraisal is given of photodielectric techniques for material property studies.

Khambaty, M. B.; Hartwig, W. H.

1972-01-01

299

Synthesis of gallium nitride nanorods through a carbon nanotube-confined reaction  

Microsoft Academic Search

Gallium nitride nanorods were prepared through a carbon nanotube-confined reaction. GaâO vapor was reacted with NHâ gas in the presence of carbon nanotubes to form wurtzite gallium nitride nanorods. The nanorods have a diameter of 4 to 50 nanometers and a length of up to 25 micrometers. It is proposed that the carbon nanotube acts as a template to confine

Weiqiang Han; Shoushan Fan; Qunqing Li; Yongdan Hu

1997-01-01

300

Phase Coexistence in Gallium Nanoparticles Controlled by Electron Excitation S. Pochon, K. F. MacDonald, R. J. Knize,* and N. I. Zheludev  

E-print Network

Phase Coexistence in Gallium Nanoparticles Controlled by Electron Excitation S. Pochon, K. F. MacBJ, United Kingdom (Received 7 November 2003; published 9 April 2004) In gallium nanoparticles 100 nm in gallium nanoparticles under electron-beam excitation. Our study of electron-beam excitation of gallium

Zheludev, Nikolay

301

By Deborah A. Kramer No gallium production was reported in the McDonnell Douglas Corp. reportedly will world producers were Australia, Germany, and  

E-print Network

1 GALLIUM By Deborah A. Kramer No gallium production was reported in the McDonnell Douglas Corp. reportedly will world producers were Australia, Germany, and United States in 1994. The U.S. gallium transition its Improved Mast Mounted Sight Russia. More than 15,000 kilograms of gallium demand was supplied

302

Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method  

SciTech Connect

Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related to their different transparency in the IR region. In gadolinium gallium garnet crystals, which are transparent to thermal radiation, a crystallization front, strongly convex toward the melt, is formed in the growth stage, which extremely rapidly melts under forced convection. Numerical analysis of this process has been performed within the quasistationary and nonstationary models. At the same time, in terbium gallium garnet crystals, which are characterized by strong absorption of thermal radiation, the phase boundary shape changes fairly smoothly and with a small amplitude. In this case, as the crystal is pulled, the crystallization front tends to become convex toward the crystal bulk.

Budenkova, O. N., E-mail: olganb@mail.ioffe.ru; Vasiliev, M. G.; Yuferev, V. S. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Ivanov, I. A.; Bul'kanov, A. M. [ZAO Research Institute of Materials Science (Russian Federation); Kalaev, V. V. [OOO Soft Impakt (Russian Federation)

2008-12-15

303

SUR LES DIAGRAMMES D'ALLIAGES DU GALLIUM I OU II AVEC L'TAIN, LE ZINC OU L'INDIUM  

E-print Network

17. SUR LES DIAGRAMMES D'ALLIAGES DU GALLIUM I OU II AVEC L'�TAIN, LE ZINC OU L'INDIUM Par Mlle S'alliages binaires du gallium I ou du gallium II avec l'étain, le zinc ou l'indium. La forme stable GaI donne des eutec- tiques avec les trois métaux. Les diagrammes de l'étain avec le gallium I ou le gallium II

Boyer, Edmond

304

Survival of rabbit platelets labeled with gallium 67  

SciTech Connect

The viability of rabbit platelets labeled with radioactive gallium was determined to analyze the feasibility of using platelets labeled with gallium 67 as an imaging reagent for positron emission tomography. Platelets were labeled with a complex of the longer lived gallium 67 and mercaptopyridine-N-oxide (MPO) or with sodium chromate Cr 51. Their survival after transfusion was measured. Labelling efficiency of /sup 67/Ga-MPO was 6.5% to 45.8% (26.8% +/- 2.8%) when platelets were suspended in saline solution, but was much lower (1.6% +/- 0.8%) in plasma. Platelets labeled with either radioisotope in a saline medium survived as well as platelets labeled with 51Cr in plasma. Recovery values 1 hour after transfusion and mean platelet survivals were 68.6% +/- 4.9% and 3.4 +/- 0.2 days for /sup 67/Ga in saline solution, 76.5% +/- 6.8% and 3.8 +/- 0.5 days for /sup 51/Cr in saline solution, and 73.7% +/- 7.4% and 3.6 +/- 0.5 days for /sup 51/Cr in plasma. Labeled platelet concentrates always contained extra radioactivity not firmly bound to viable platelets. A postlabeling wash in saline solution did not reduce this contamination and resulted in reduction of the number of viable platelets. The results showed that rabbit platelets labeled with /sup 67/Ga-MPO survived in the circulation as well as those labeled by a standard protocol with sodium chromate Cr 51.

Mazoyer, E.; Carpenter, D.; Ebbe, S.; Yano, Y.; Dalal, K.; Singh, M.; Mazoyer, B.

1988-02-01

305

Gallium-68 chemistry for labeling platelets, proteins and lipoproteins  

SciTech Connect

Generator produced gallium-68 is a convenient useful radionuclide for positron emission tomography (PET) investigations. Gallium-68 labeled platelets and low density lipoproteins would be useful agents for PET studies of thrombosis and atherosclerosis in cardiovascular disease. To label these agents with Ga-68, we have studied the effects of trace metal contaminants in 1 N HCl elutions of Ga-68 from germanium-68 absorbed on a stannic oxide column. Studies were conducted on the formation and characteristics of Ga-68 complexes with the ligands 8-hydroxyquinoline, tropolone, and mercaptopyridine-N-oxide (MPO). Various parameters such as pH, buffers, concentration of ligand, and incubation or stability with time were investigated. High performance liquid chromatography and instant thin layer chromatography were used to analyze the Ga-68 ligand preparations. Platelets separated from human, dog, and rabbit plasma were incubated with the Ga-68 complexes and the labeling yields and in vivo survival were determined. The accumulation of the platelets in the ballon catheter scraped aorta of the rabbit was determined by PET imaging studies, tissue counting in a gamma well counter, and en-face autoradiography of the arterial wall. The Ga-68 complexes of MPO gave 40 to 60% labeling efficiency of rabbit platelets which accumulated about fourfold more in the damaged aorta compared to the normal. Gallium-68 was attached to low density lipoproteins (LDL) with the bifunctional chelate of DTPA. Low pressure gel column chromatography and HPLC were used to preparatively separate and analyze the Ga-68 LDL for uptake studies in the healing endothelium of the scraped aorta rabbit model. The Ga-68 LDL labeling yield was 80 to 85% with a radiochemical purity 90 to 95%. 22 references, 10 figures, 4 tables.

Yano, Y.; Budinger, T.F.; Ebbe, S.N.; Mathis, C.A.; Moore, D.H.; Singh, M.; Brennan, K.; Moyer, B.R.; Nichols, A.

1984-07-01

306

Convenient synthesis of aluminum and gallium phosphonate cages.  

PubMed

The reactions of AlCl 3.6H 2O and GaCl 3 with 2-pyridylphosphonic acid (2PypoH 2) and 4-pyridylphosphonic acid (4PypoH 2) afford cyclic aluminum and gallium phosphonate structures of [(2PypoH) 4Al 4(OH 2) 12]Cl 8.6H 2O ( 1), [(4PypoH) 4Al 4(OH 2) 12]Cl 8.11H 2O ( 2), [(2PypoH) 4Al 4(OH 2) 12](NO 3) 8.7H 2O ( 3), [(2PypoH) 2(2Pypo) 4Ga 8Cl 12(OH 2) 4(thf) 2](GaCl 4) 2..8thf ( 4), and [(2PypoH) 2(2Pypo) 4Ga 8Cl 12(OH 2) 4(thf) 2](NO 3) 2.9thf ( 5). Structures 1- 3 feature four aluminum atoms bridged by oxygen atoms from the phosphonate moiety and show structural resemblance to the secondary building units found in zeolites and aluminum phosphates. The gallium complexes, 4 and 5, have eight gallium atoms bridged by phosphonate moieties with two GaCl 4 (-) counterions present in 4 and nitrate ions in 5. The cage structures 1- 3 are interlinked by strong hydrogen bonds, forming polymeric chains that, for aluminum, are thermally robust. Exchange of the phosphonic acid for the more flexible 4PyCH 2PO 3H 2 afforded a coordination polymer with a 1:1 Ga:P ratio, {[(4PyCH 2PO 3H)Ga(OH 2) 3](NO 3) 2.0.5H 2O} x ( 6). Complexes 1- 6 were characterized by single-crystal X-ray diffraction, NMR, and mass spectrometry and studied by TGA. PMID:18366160

Samanamu, Christian R; Olmstead, Marilyn M; Montchamp, Jean-Luc; Richards, Anne F

2008-05-01

307

Alloying of Ni\\/In\\/Ni\\/n-GaAs ohmic contacts induced by Ga-Ni-As ternary eutectic reactions  

Microsoft Academic Search

The alloying behavior of Ni and Ni\\/In\\/Ni thin-film contacts to GaAs was studied using scanning electron microscopy and scanning Auger microscopy. A liquid was observed to form in both contacts upon annealing at 820 °C for three min. The cause of this behavior was postulated to be the presence of a ternary eutectic reaction in the gallium-nickel-arsenic system. Differential thermal

C.-H. Jan; D. Swenson; Y. A. Chang

1990-01-01

308

Plastic deformation modes of gallium arsenide in nanoindentation and nanoscratching  

NASA Astrophysics Data System (ADS)

The mechanical deformation by nanoindentation and scratching of gallium arsenide has been investigated using cross-sectional transmission electron microscopy. Twinning was found to be the main deformation process occurring during indentation while only slip bands and perfect dislocations are observed during scratching. This behavior is explained, in the authors' experiments, with the strain rate in scratching being hundred times greater than in indentation. Hence, the low indentation velocity allows twins to be nucleated and propagated from surface inhomogeneities, whereas in scratching, the deformation occurs first in front of the indenter and the scratching speed allows only perfect ? dislocation to propagate.

Wasmer, K.; Parlinska-Wojtan, M.; Gassilloud, R.; Pouvreau, C.; Tharian, J.; Micher, J.

2007-01-01

309

Aluminum and gallium hydrazides as precursors to metal nitride semiconductors  

NASA Astrophysics Data System (ADS)

The solution phase reaction chemistry of aluminum and gallium alkyls with a variety of hydrazines has been explored. Substitution patterns include unsubstituted, symmetric and unsymmetric disubstituted and monosubstituted hydrazines. Both the size and the electronic characteristics of the hydrazine substituents were varied. All three factors---size, electronics, and pattern---were found to influence the initial reaction products and subsequent thermolysis products. In most cases, the first product isolated was a Lewis acid-base adduct which was characterized by spectroscopic methods. Thermolysis of the adduct led to elimination of alkane from the metal and the formation of a new product which was characterized crystallographically. In the case of unsymmetric disubstituted hydrazines, the product was determined to be a dimeric ring of the formula (R2MNHNR'2)2. Bulky monosubstituted hydrazines led to a dimeric ring as well while further thermolysis resulted in a second alkane elimination and the formation of a cage structure with the formula (RMNHNR')4. Monosubstituted hydrazines with smaller substituents, formed a double-ringed complex of the formula ((R2Ga)2NHNHR')2NHNR ' upon thermolysis with gallium alkyls. Evidence for the reduction of acetonitrile with Me3Ga and unsubstituted hydrazine was observed, and the product characterized by X-ray crystallography. With one exception, symmetric disubstituted hydrazines formed symmetric products upon reaction with gallium or aluminum alkyls. The exception, Et3Al, formed an aluminum-nitrogen cubane upon thermolysis with 1,2-diphenylhydrazine. The addition of a second equivalent of alkyl metal to the dimers described above led to a new species, (Me3M)2:(Me2MNHNMe 2)2, with both covalent and dative bonds, or a ladder type compound, (Me2NN(Me2Al)2MeAlNNMe2) 2, if Me3Al was added to the aluminum dimer. In addition, a mixed metal compound of the formula (Me2MNHNMe2) 2 M = Ga/Al was synthesized by simple mixing of the dimers in solution. Thermal degradation of the products characterized above was carried out by thermogravimetric analyses and bulk scale thermolysis under a variety of gasses. The results were evaluated by X-ray powder diffraction. Gallium nitride formation was demonstrated with several of the products at temperatures as low as 600°C.

Peters, David Walter

2000-10-01

310

Self-diffusion in liquid gallium and hard sphere model  

NASA Astrophysics Data System (ADS)

Incoherent and coherent components of quasielastic neutron scattering have been studied in the temperature range of T = 313 K - 793 K aiming to explore the applicability limits of the hard-sphere approach for the microscopic dynamics of liquid gallium, which is usually considered as a non-hard-sphere system. It was found that the non-hard-sphere effects come into play at the distances shorter than the average interatomic distance. The longer range diffusive dynamics of liquid Ga is dominated by the repulsive forces between the atoms.

Blagoveshchenskii, Nikolay; Novikov, Arkady; Puchkov, Alexander; Savostin, Vadim; Sobolev, Oleg

2015-01-01

311

Spectroscopy of vanadium (III) doped gallium lanthanum sulphide chalcogenide glass  

E-print Network

Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 730 and 1155 nm identified by photoluminescence excitation measurements. Broad photoluminescence, with a full width half maximum (FWHM) of 500 nm, is observed peaking at 1500 nm when exciting at 514, 808 and 1064 nm. The fluorescence lifetime and quantum efficiency at 300 K were measured to be 33.4 us and 4 % respectively. From the available spectroscopic data we propose the vanadium ions valence to be 3+ and be in tetrahedral coordination The results indicate potential for development of a laser or optical amplifier based on V:GLS.

Hughes, M; Rutt, H; Hewak, D

2014-01-01

312

Testing of gallium arsenide solar cells on the CRRES vehicle  

NASA Technical Reports Server (NTRS)

A flight experiment was designed to determine the optimum design for gallium arsenide (GaAs) solar cell panels in a radiation environment. Elements of the experiment design include, different coverglass material and thicknesses, welded and soldered interconnects, different solar cell efficiencies, different solar cell types, and measurement of annealing properties. This experiment is scheduled to fly on the Combined Release and Radiation Effects Satellite (CRRES). This satellite will simultaneously measure the radiation environment and provide engineering data on solar cell degradation that can be directly related to radiation damage.

Trumble, T. M.

1985-01-01

313

Proton-Implanted Planar Waveguide in Gallium Lanthanum Sulphide Glass  

NASA Astrophysics Data System (ADS)

Owing to the remarkable properties of chalcogenide glasses, chalcogenide optical waveguides should play a significant role in the development of integrated optics. This work demonstrates that an optical waveguide can be obtained by a simple proton implantation in gallium lanthanum sulphide (GLS) glass. Two modes exist in the waveguide at a wavelength of 632.8 nm and the refractive index profile of the waveguide is reconstructed. The near-field pattern of the transmitted light is obtained, and the propagation loss is about 3.2 dB/cm for the present waveguide.

Qiu, Feng; Narusawa, Tadashi

2010-09-01

314

Gallium uptake in tryptophan-related pulmonary disease  

SciTech Connect

We describe a patient who developed fever, fatigue, muscle weakness, dyspnea, skin rash, and eosinophilia after taking high doses of tryptophan for insomnia for two years. A gallium-67 scan revealed diffuse increased uptake in the lung and no abnormal uptake in the muscular distribution. Bronchoscopy and biopsy confirmed inflammatory reactions with infiltration by eosinophils, mast cells, and lymphocytes. CT scan showed an interstitial alveolar pattern without fibrosis. EMG demonstrated diffuse myopathy. Muscle biopsy from the right thigh showed an inflammatory myositis with eosinophilic and lymphocytic infiltrations.

Kim, S.M.; Park, C.H.; Intenzo, C.M.; Patel, R. (Thomas Jefferson Univ. Hospital, Philadelphia, PA (USA))

1991-02-01

315

Improved performance design of gallium arsenide solar cells for space  

NASA Technical Reports Server (NTRS)

An improved design, shallow junction heteroface, n-p, gallium arsenide solar cell for space applications is reported, with a predicted AM0 efficiency in the 21.9 to 23.0 percent range. The optimized n-p structure, while slightly more efficient, has the added advantage of being less susceptible to radiation-induced degradation by virtue of this thin top junction layer. Detailed spectral response curves and an analysis of the loss mechanisms are reported. The details of the design are readily measurable. The optimized designs were reached by quantifying the dominant loss mechanisms and then minimizing them by using computer simulations.

Parekh, R. H.; Barnett, A. M.

1984-01-01

316

VAl Alloy  

NASA Astrophysics Data System (ADS)

Power generation performance of a thermoelectric module consisting of the Heusler Fe2VAl alloy was evaluated. For construction of the module, W-doped Fe2VAl alloys were prepared using powder metallurgy process. Power generation tests of the module consisting of 18 pairs of p- n junctions were conducted on a heat source of 373-673 K in vacuum. The reduction of thermal conductivity and improvement of thermoelectric figure of merit by W-doping enhanced the conversion efficiency and the output power. High output power density of 0.7 W/cm2 was obtained by virtue of the high thermoelectric power factor of the Heusler alloy. The module exhibited good durability, and the relatively high output power was maintained after temperature cycling test in air.

Mikami, M.; Mizoshiri, M.; Ozaki, K.; Takazawa, H.; Yamamoto, A.; Terazawa, Y.; Takeuchi, T.

2014-06-01

317

Electrical Conductivity of Graphene Composites with In and In-Ga Alloy  

NASA Astrophysics Data System (ADS)

Samples of composites of graphene with indium or indium-gallium alloy as the matrix were prepared by a process of spreading exfoliated graphene oxide on the foils, repeatedly folding and rolling. The foils were intermittently annealed and the process repeated by addition of more graphene oxide. Indium flux was used to remove any indium or gallium oxide. The samples were characterized by x-ray diffraction, and optical and scanning electron microscopy (SEM). Electrical resistivity and temperature coefficient of resistance (TCR) were measured using a four-probe method in the temperature range of 260 K to 340 K, and the results were used to determine the volume fraction of graphene from effective mean-field analysis. The volume fraction of graphene remained between 0.11 and 0.14 in samples of In with graphene and between 0.12 and 0.13 in samples of In-Ga with graphene. The results indicate that the electrical resistivity and the TCR of the composite were reduced by the addition of graphene. The resistivity of graphene remained between 1.19 × 10-6 ohm cm and 1.87 × 10-6 ohm cm in all samples and was thus almost independent of the matrix composition. The electrical resistivity of graphene was found to be an order of magnitude smaller than that of indium or the indium-gallium alloy.

Sruti, A. Naga; Jagannadham, K.

2010-08-01

318

Technetium-99m DTPA aerosol and gallium scanning in acquired immune deficiency syndrome  

SciTech Connect

In 11 non-smoking AIDS patients suspected of pneumocystis carinii pneumonia (PCP), the results of Tc-99m DTPA aerosol clearances, gallium scans, and arterial blood gases were compared with those of bronchoalveolar lavage (BAL). Nine patients had PCP. All had increased clearances five times higher than the normal (5.6 +/- 2.3% X min-1 vs 1.1 +/- 0.34% X min-1, N = 10, P less than 0.001), suggesting an increased alveolar permeability. Gallium scans were abnormal in six patients but normal or slightly abnormal in the three others. Four of these nine patients had normal chest x-rays. In two of these the gallium scan was abnormal, but in the two others, only the increased Tc-99m DTPA clearances showed evidence of lung disease. Two patients had normal BAL, with normal clearances and gallium scans. Four out of the nine patients with PCP were studied after treatment. Three recovered and had normal clearance and gallium scans. One still had PCP with increased clearance but normal gallium scan. Gallium scanning and Tc-99m DTPA clearance are useful for detecting lung disease in AIDS patients with suspected PCP and for prompting BAL when chest x-rays and PaO/sub 2/ levels are normal. Due to its high sensitivity, a normal Tc-99m DTPA clearance could avoid BAL.

Picard, C.; Meignan, M.; Rosso, J.; Cinotti, L.; Mayaud, C.; Revuz, J.

1987-07-01

319

Gallium-containing phospho-silicate glasses: synthesis and in vitro bioactivity.  

PubMed

A series of Ga-containing phospho-silicate glasses based on Bioglass 45S5, having molar formula 46.2SiO2·24.3Na2O·26.9CaO·2.6P2O5·xGa2O3 (x=1.0, 1.6, 3.5), were prepared by fusion method. The reference Bioglass 45S5 without gallium was also prepared. The synthesized glasses were immersed in simulated body fluid (SBF) for 30 days in order to observe ion release and hydroxyapatite (HA) formation. All Ga-containing glasses maintain the ability of HA formation as indicated by main X-ray diffractometric peaks and/or electronic scanning microscopy results. HA layer was formed after 1 day of SBF soaking in 45S5 glass containing up to 1.6% Ga2O3 content. Moreover, gallium released by the glasses was found to be partially precipitated on the glass surface as gallium phosphate. Further increase in gallium content reduced the ion release in SBF. The maximum of Ga(3+) concentration measured in solution is ~6 ppm determined for 3.5% Ga2O3 content. This amount is about half of the toxic level (14 ppm) of gallium and the glasses release gallium till 30 days of immersion in SBF. Considering the above results, the studied materials can be proposed as bioactive glasses with additional antimicrobial effect of gallium having no toxic outcome. PMID:24364938

Franchini, Mirco; Lusvardi, Gigliola; Malavasi, Gianluca; Menabue, Ledi

2012-08-01

320

Iron-Targeting Antitumor Activity of Gallium Compounds and Novel Insights Into Triapine®-Metal Complexes  

PubMed Central

Abstract Significance: Despite advances made in the treatment of cancer, a significant number of patients succumb to this disease every year. Hence, there is a great need to develop new anticancer agents. Recent Advances: Emerging data show that malignant cells have a greater requirement for iron than normal cells do and that proteins involved in iron import, export, and storage may be altered in cancer cells. Therefore, strategies to perturb these iron-dependent steps in malignant cells hold promise for the treatment of cancer. Recent studies show that gallium compounds and metal-thiosemicarbazone complexes inhibit tumor cell growth by targeting iron homeostasis, including iron-dependent ribonucleotide reductase. Chemical similarities of gallium(III) with iron(III) enable the former to mimic the latter and interpose itself in critical iron-dependent steps in cellular proliferation. Newer gallium compounds have emerged with additional mechanisms of action. In clinical trials, the first-generation-compound gallium nitrate has exhibited activity against bladder cancer and non-Hodgkin's lymphoma, while the thiosemicarbazone Triapine® has demonstrated activity against other tumors. Critical Issues: Novel gallium compounds with greater cytotoxicity and a broader spectrum of antineoplastic activity than gallium nitrate should continue to be developed. Future Directions: The antineoplastic activity and toxicity of the existing novel gallium compounds and thiosemicarbazone-metal complexes should be tested in animal tumor models and advanced to Phase I and II clinical trials. Future research should identify biologic markers that predict tumor sensitivity to gallium compounds. This will help direct gallium-based therapy to cancer patients who are most likely to benefit from it. Antioxid. Redox Signal. 00, 000–000. PMID:22900955

Antholine, William E.

2013-01-01

321

High-surface Thermally Stable Mesoporous Gallium Phosphates Constituted by Nanoparticles as Primary Building Blocks  

SciTech Connect

In constant, search for micro/mesoporous materials, gallium phosphates, have attracted continued interest due to the large pore size reported for some of these solids in comparison with analogous aluminum phosphates. However up to now, the porosity of gallium phosphates collapsed upon template removal or exposure to the ambient moisture. In the present work, we describe high-surface thermally stable mesoporous gallium phosphates synthesized from gallium propoxide and PCl{sub 3} and different templating agents such as amines (dipropylamine, piperidine and aminopiperidine) and quaternary ammonium salts (C{sub 16}H{sub 33}(CH{sub 3})3NBr and C{sub 16}PyCl). These highly reactive precursors have so far not been used as gallium and phosphate sources for the synthesis of gallophosphates. Conceptually, our present synthetic procedure is based on the fast formation of gallium phosphate nanoparticles via the reaction of gallium propoxide with PCl{sub 3} and subsequent construction of the porous material with nanoparticles as building blocks. The organization of the gallophosphate nanoparticles in stable porous structures is effected by the templates. Different experimental procedures varying the molar composition of the sol-gel, pH and the pretreatment of gallium precursor were assayed, most of them leading to satisfactory materials in terms of thermal stability and porosity. In this way, a series of gallium phosphates with surface are above 200 m{sup 2} g{sup -1}, and narrow pore size from 3 to 6 nm and remarkable thermal stability (up to 550 C) have been prepared. In some cases, the structure tends to show some periodicity and regularity as determined by XRD. The remarkable stability has allowed us to test the catalytic activity of gallophosphates for the aerobic oxidation of alkylaromatics with notable good results. Our report reopens the interest for gallophosphates in heterogeneous catalysis.

V Parvulescu; V Parvulescu; D Ciuparu; C Hardacre; H Garcia

2011-12-31

322

Raman and Photoluminescence Spectroscopy of Gallium Oxide Nanostructures  

NASA Astrophysics Data System (ADS)

Gallium oxide is a wide band gap material ( ˜4.8 eV) with unique electronic and optical properties. Here we report the synthesis of gallium oxide nanostructures, such as nanobelts and nanowires using the thermal or microwave plasma CVD reactor^1. High-resolution TEM, electron diffraction and Raman analysis showed the structure of the nanowires to be that of the monoclinic (?-Ga2O3) phase. The nanowire diameters ranged from 10-100nm in diameter with lengths up to several microns. Preliminary micro-Raman analysis of the nanowires (produced by the plasma CVD) using laser excitation wavelengths of 442nm, 514.5nm and 785nm showed an upshift of ˜10-15 cm-1 in the frequency of the dominant ˜200 cm^1 (A_g) peak. Room temperature photoluminescence spectra of these nanowires suspended in iso-propyl alcohol showed a dominant emission band ˜325 nm. ^1S. Sharma, and M. K. Sunkara, J. Amer. Chem. Soc., 124, 12288 (2002).

Rao, R.; Sharma, S.; Sunkara, M. K.; Chen, B.; Zhou, B.; Sun, Y.-P.; Rao, A. M.

2003-03-01

323

Magnetorotational Instability in a Short Couette Flow of Liquid Gallium  

NASA Astrophysics Data System (ADS)

A concise review is given of an experimental project to study magnetorotational instability (MRI) in a short Couette geometry using liquid gallium. Motivated by the astrophysical importance and lack of direct observation of MRI in nature and in the laboratory, a theoretical stability analysis was performed to predict the required experimental parameters. Despite the long-wavelength nature of MRI, local analysis agrees excellently with global eigenmode calculations when periodic boundary conditions are used in the axial direction. To explore the effects of rigidly rotating vertical boundaries (endcaps), a prototype water experiment was conducted using dimensions and rotation rates favored by the above analysis. Significant deviations from the expected Couette flow profiles were found. The cause of the discrepancy was investigated by nonlinear hydrodynamic simulations using realistic boundary conditions. It was found that Ekman circulation driven by the endcaps transports angular momentum and qualitatively modifies the azimuthal flow. Based on this new understanding, a new design was made to incorporate two independently driven rings at each endcap. Simulations were used to optimize the design by minimizing Ekman circulation while remaining within engineering capabilities. The new apparatus, which has been constructed and assembled, is currently being tested with water and will be ready for the MRI experiment with gallium soon. This development process illustrates the value of interplay between experiment, simulation, and analytic insight.

Ji, Hantao; Goodman, Jeremy; Kageyama, Akira; Burin, Michael; Schartman, Ethan; Liu, Wei

2004-11-01

324

Gadolinium Gallium Garnet at Multi-Megabar Pressures  

NASA Astrophysics Data System (ADS)

Gadolinium gallium oxide Gd3Ga5O12, which crystallizes in the garnet structure, has recently attracted strong interest due to shock-wave experiments revealing a highly incompressible high-pressure phase above 1 Mbar [1]. In addition, recent diamond-cell x-ray diffraction experiments provide evidence for a phase transition from garnet to double-perovskite structures around 1 Mbar [2]. We present the results of laser-driven shock experiments on gadolinium gallium garnet (GGG) at pressures of 3 to more than 20 Mbar, obtained at the Omega-LLE and Jupiter-LLNL facilities, and compare these with the results of ab-initio molecular dynamic simulations. Velocimetry (VISAR) and pyrometry (SOP) diagnostics, and an impedance match analysis with quartz standards, provide data on the equation of state, temperature and optical reflectivity at 532 nm. No obvious phase transition is detected in the explored pressure range, but the data indicate that GGG remains surprisingly stiff up to more than 20 Mbar. We observe metallic-like reflectivity in the ultra-high pressure (possibly liquid) regime. This study could be relevant for planetary interior modeling, as many Earth and super-Earth minerals adopt the garnet and perovskite structures, and may exhibit transition to metallic and highly incompressible behavior.

Millot, M.; Ali, S. J.; Militzer, B.; Barrios, M. A.; Boehly, T.; Eggert, J. H.; Collins, G.; Jeanloz, R.

2011-12-01

325

Gallium phosphide high-temperature bipolar junction transistor  

SciTech Connect

Preliminary results are reported on the development of a high-temperature (> 350/sup 0/C) gallium phosphide bipolar junction transistor (BJT) for goethermal and other energy applications. This four-layer p/sup +/n/sup -/pp/sup +/ structure was fromed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into the lightly doped base. By appropriate choice of electrodes, the device may also be driven as an n-channel junction field-effect transistor. The gallium phosphide BJT is observed to have a common-emitter current gain peaking in the range of 6 to 10 (for temperatures from 20/sup 0/C to 400/sup 0/C) and a room-temperature, punchthrough-limited, collector-emitter breakdown voltage of approximately -6V. Other parameters of interest include an f/sub/ = 400 KHz (at 20/sup 0/C) and a collector base leakage current = 200 ..mu..A (at 350/sup 0/C).

Zipperian, T.E.; Dawson, L.R.; Caffin, R.J.

1981-03-01

326

The Effect of Gallium Nitrate on Arresting Blood Flow from a Wound  

PubMed Central

A novel application of gallium nitrate, hitherto unreported, in reducing bleeding time from an open wound is presented. Experiments performed using simple punctures in the forearm demonstrated a very substantial reduction in bleeding time when a solution of gallium nitrate was applied relative to a control. This outcome was shown to be unaffected by the anticoagulant properties of warfarin. The mechanism for such action of gallium nitrate is unknown and merits further investigation, as do the possibilities for such an application to improve both civilian and defense trauma treatment modalities. PMID:21629814

Goodley, Paul H.; Rogosnitzky, Moshe

2011-01-01

327

Concerning the energy levels of silver in Ge-Si alloys  

SciTech Connect

The emission from impurity states of silver (an element of the IB subgroup) in a Ge-Si alloy, containing 18 at % Si, has been studied. The donor level of silver has been found in crystals doubly doped with gallium and silver, while its first acceptor level has been revealed in crystals doped with only silver. Single crystals were grown by pulling from a melt using a feeding rod. Doping with gallium was performed by introducing this element into the feeding rod, and silver was introduced into the crystals via diffusion. The positions of the donor and first acceptor Ag levels with respect to the top of the valence band were found by analyzing the temperature dependence of the Hall coefficient and the electroneutrality equation for the crystal: 0.06 and 0.29 eV, respectively.

Tahirov, V. I. [Baku State University (Azerbaijan); Agamaliev, Z. A. [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan); Sadixova, S. R.; Guliev, A. F.; Gahramanov, N. F., E-mail: n_gakhramanov@mail.ru [Sumgait State University (Azerbaijan)

2012-03-15

328

Chemical ordering in AlGaN alloys grown by molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

Aluminum gallium nitride alloys were grown by molecular beam epitaxy and their film composition, structure, and microstructure were investigated by Rutherford backscattering spectroscopy, atomic force microscopy, x-ray diffraction, and transmission electron microscopy. It was found that the ratio of group-III to group-V fluxes influences the relative incorporation of gallium and aluminum in the films. The transmission electron microscopy and x-ray diffraction studies revealed the existence of three types of spontaneously formed superlattice structures with periodicities of 2, 7, and 12 ML. While the 2 ML ordering is preferred under group-V rich conditions of growth, the 7 and 12 ML orderings were observed under group-III rich conditions of growth.

Iliopoulos, E.; Ludwig, K. F.; Moustakas, T. D.; Chu, S. N. G.

2001-01-01

329

Real-time in-situ chemical sensing in aluminum gallium nitride/gallium nitride metal-organic chemical vapor deposition processes for advanced process control  

NASA Astrophysics Data System (ADS)

Gallium nitride and its alloys promise to be key materials for future semiconductor devices aimed at high frequency, high power electronic applications. However, manufacturing for such high performance products is challenged by reproducibility and material quality constraints that are notably more stringent than those required for optoelectronic applications. To meet this challenge, in-situ mass spectrometry was implemented as a real-time process- and wafer-state metrology tool in AlGaN/GaN/AlN metal-organic chemical vapor deposition processes on semi-insulating SiC substrate wafers. Dynamic chemical sensing through the process cycle, carried out downstream from the wafer, revealed generation of methane and ethane reaction byproducts, as well as other residual gas species. Real-time metrics were derived based on the chemical signals to predict/control material quality and thickness of critical layers within the heterostructure in real time during growth, and corresponding metrologies were used for real-time advanced process control. Using the methane/ethane ratio, GaN epilayer crystal quality was predicted in real time to 2--5% precision, which was verified by post-process x-ray diffraction. Moreover, the same real-time metric predicted material quality as indicated by post-process photoluminescence band-edge intensities to ˜5% precision. The methane/ethane ratio has a fundamental significance in terms of the intrinsic chemistry in that the two byproducts are believed to reflect two parallel reaction pathways leading to GaN-based material growth, namely the gas phase adduct formation route and the surface route for direct precursor decomposition, respectively. The fact that lower methane/ethane ratios consistently yield better material quality suggests that the surface pathway is preferred for high quality GaN growth. In addition, a metric based on methane and ethane signals integrated through the AlGaN growth period (˜1 min or less) enabled prediction of the cap layer thickness (˜20 nm) to within ˜1% precision, which was verified by post-process x-ray reflectance. These types of real-time advanced process control activities in terms of fault detection and management, course correction, and pre-growth contamination control have made significant contributions to the GaN-based semiconductor development and manufacturing at Northrop Grumman Electronics Systems in terms of improved material quality, yield, and consequent cost reduction, and they are now in routine use.

Cho, Soon

330

Luminescence dynamics and waveguide applications of europium doped gallium nitride powder  

E-print Network

Luminescence dynamics and waveguide applications of europium doped gallium nitride powder Carl B, bismuth shot, and europium ingot in an ammonia ambient to initially obtain chunks of the desired material

Lipson, Michal

331

Renal gallium accumulation in the absence of renal pathology in patients with severe hepatocellular disease  

SciTech Connect

Visualization of Ga-67 citrate in the kidneys at 48 hours and 72 hours post injection is usually interpreted as evidence of renal pathology. In reviewing approximately 200 consecutive patients referred for gallium scans, 40 patients who also underwent liver/spleen Tc-99m sulfur colloid (SC) studies within one month of the gallium study were identified. Fourteen of these patients showed advanced hepatocellular dysfunction on the Tc-99m SC liver/spleen images. Of these 14 patients, nine had persistent renal accumulation of gallium at 48 or 72 hours. Five of these nine patients had no evidence of primary renal disease by clinical or postmortem examination and subsequent clinical information indicated that two additional patients probably had no significant renal pathology. Therefore, bilateral symmetrically increased renal uptake of gallium in patients with advanced hepatocellular disease should not necessarily be interpreted as evidence of renal pathology.

Alazraki, N.; Sterkel, B.; Taylor, A. Jr.

1983-05-01

332

Limits on ?e and ?¯e disappearance from Gallium and reactor experiments  

NASA Astrophysics Data System (ADS)

The deficit observed in the Gallium radioactive source experiments is interpreted as a possible indication of the disappearance of electron neutrinos. In the effective framework of two-neutrino mixing we obtain sin?22??0.03 and ?m2?0.1eV2. The compatibility of this result with the data of the Bugey and Chooz reactor short-baseline antineutrino disappearance experiments is studied. It is found that the Bugey data present a hint of neutrino oscillations with 0.02?sin?22??0.08 and ?m2?1.8eV2, which is compatible with the Gallium allowed region of the mixing parameters. This hint persists in the combined analyses of Bugey and Chooz data, of Gallium and Bugey data, and of Gallium, Bugey, and Chooz data.

Acero, Mario A.; Giunti, Carlo; Laveder, Marco

2008-10-01

333

Radiology of pulmonary disease. Chest radiography, computed tomography, and gallium scanning  

SciTech Connect

A review of the radiologic manifestations of AIDS pulmonary diseases, with an emphasis on the utility of gallium scanning in the context of the normal or equivocal chest x-ray, is presented.99 references.

Golden, J.A.; Sollitto, R.A.

1988-09-01

334

Radiology of pulmonary disease. Chest radiography, computed tomography, and gallium scanning  

Microsoft Academic Search

A review of the radiologic manifestations of AIDS pulmonary diseases, with an emphasis on the utility of gallium scanning in the context of the normal or equivocal chest x-ray, is presented.99 references.

J. A. Golden; R. A. Sollitto

1988-01-01

335

Studies on controlled potential coulometric determination of gallium in sodium perchlorate and sodium thiocyanate.  

PubMed

Controlled potential coulometric (CPC) studies were carried out for developing a method to determine gallium at milligram levels, in the mixed supporting electrolyte medium (4M NaClO(4)+0.5M NaSCN), employing stirring mercury as a working electrode. Investigations for optimization of working electrode potentials, quantity of charge, level of background current and electrolysis time for achieving quantitative reduction of Ga(III) to Ga and its oxidation back to Ga(III), were undertaken. Effect of gallium content and interference of zinc in of gallium determination were also studied. The developed methodology was employed for the determination of gallium in pure Ga as well as in synthetic U+Ga mixture solutions. Accuracy and precision values of better than 0.5% were obtained at 1-2mg levels. PMID:19071443

Sharma, H S; Bhardwaj, T K; Jain, P C; Aggarwal, S K

2007-02-28

336

Process for producing gallium-containing solution from the aluminum smelting dust  

SciTech Connect

A process is described for producing a gallium-containing solution from aluminum smelting dust comprising leaching aluminum smelting dust with a mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid and nitric acid, and adding an oxidizing agent to the aluminum smelting dust at the time of leaching to preferentially leach and extract gallium from the aluminum smelting dust without extracting aluminum from the aluminum smelting dust. The oxidizing agent is selected from the group consisting of potassium permanganate, manganese dioxide, hydrogen peroxide, ozone, potassium chromate, potassium dichromate, ammonium persulfate, sodium hydrochlorite, sodium chlorite and sodium chlorate. The leached aluminum smelting dust is filtered to obtain a gallium-containing solution of dissolved gallium.

Era, A.; Matsui, S.; Ikeda, H.

1988-03-01

337

Utility of gallium imaging of the kidneys in diagnosing primary amyloid nephrotic syndrome  

SciTech Connect

We undertook a study to determine the value of gallium imaging of the kidneys in patients who had primary amyloidosis that was manifest clinically by nephrotic syndrome. We studied 28 patients with gallium-67 (67Ga) citrate scans performed 48 hr after injection. Intense (3+ to 4+) uptake was noted in both kidneys in 25 of 28 patients. Renal amyloidosis should be considered in the differential diagnosis when diffuse bilateral renal uptake of (67Ga)citrate is seen in the setting of nephrotic syndrome. Gallium uptake did not differentiate amyloid nephrotic syndrome from other causes of nephrotic syndrome. Renal gallium uptake showed a weak correlation with 24-hr urine protein excretion (p = 0.06).

Gertz, M.A.; Brown, M.L.; Hauser, M.F.; Kyle, R.A. (Mayo Clinic, Rochester, MN (USA))

1990-03-01

338

Spectroscopic, optical, and thermomechanical properties of neodymium- and chromium-doped gadolinium scandium gallium garnet  

Microsoft Academic Search

Spectroscopic, optical, and thermomechanical properties of gadolinium scandium gallium garnet doped with trivalent neodymium and\\/or chromium are reported for use in the design of high-power solid-state lasers.

W. F. Krupke; M. D. Shinn; J. E. Marion; J. A. Caird; S. E. Stokowski

1986-01-01

339

Limits on nu_e and anti-nu_e disappearance from Gallium and reactor experiments  

E-print Network

The deficit observed in the Gallium radioactive source experiments is interpreted as a possible indication of the disappearance of electron neutrinos. In the effective framework of two-neutrino mixing we obtain $\\sin^{2}2\\vartheta \\gtrsim 0.03$ and $\\Delta{m}^{2} \\gtrsim 0.1 \\text{eV}^{2}$. The compatibility of this result with the data of the Bugey and Chooz reactor short-baseline antineutrino disappearance experiments is studied. It is found that the Bugey data present a hint of neutrino oscillations with $0.02 \\lesssim \\sin^{2}2\\vartheta \\lesssim 0.08$ and $\\Delta{m}^{2} \\approx 1.8 \\text{eV}^{2}$, which is compatible with the Gallium allowed region of the mixing parameters. This hint persists in the combined analyses of Bugey and Chooz data, of Gallium and Bugey data, and of Gallium, Bugey, and Chooz data.

Mario A. Acero; Carlo Giunti; Marco Laveder

2008-09-17

340

Bit-systolic arithmetic arrays using dynamic differential gallium arsenide circuits  

NASA Technical Reports Server (NTRS)

A new family of gallium arsenide circuits for fine grained bit-systolic arithmetic arrays is introduced. This scheme combines features of two recent techniques of dynamic gallium arsenide FET logic and differential dynamic single-clock CMOS logic. The resulting circuits are fast and compact, with tightly constrained series FET propagation paths, low fanout, no dc power dissipation, and depletion FET implementation without level shifting diodes.

Beagles, Grant; Winters, Kel; Eldin, A. G.

1992-01-01

341

First Results of the Testing of the Liquid Gallium Jet Limiter Concept for ISTTOK  

SciTech Connect

The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages to the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaustion from fusion devices. Presently the most promising materials are Lithium and Gallium. ISTTOK, a small size tokamak, will be used to test the behavior of a liquid Gallium jet in the vacuum chamber and its influence on the plasma. This paper presents a description of the conceived setup as well as experimental results. The liquid Gallium jet is generated by hydrostatic pressure and injected in a radial position close to a moveable stainless steel limiter. Both the jet and the limiter positions are variable allowing for a controlled exposure of the liquid Gallium to the edge plasma. The main components of the Gallium loop are a MHD pump, the liquid metal injector and a filtering system. The MHD pump is of the induction type, based on rotating permanent magnets. The injector is build from a stainless steel pipe ended by a shaping nozzle. A setup has been developed to introduce oxide-free Gallium inside the loop's main supply tank. Raw liquid metal is placed inside a chamber heated and degassed under high vacuum while clean Gallium is extracted from the main body of the liquefied metal. Prior to installation on the tokamak, the experimental rig has been implemented using a Pyrex tube as test chamber to investigate the stability of the Gallium jet and its break-up length for several nozzle sizes. Results are presented in this paper. This rig was also useful to assess the behavior of the overall implemented apparatus.

Gomes, R. B.; Fernandes, H.; Silva, C.; Borba, D.; Carvalho, B.; Varandas, C. [Associacao EURATOM/IST, Centro de FuSao Nuclear, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Lielausis, O.; Klyukin, A.; Platacis, E.; Mikelsons, A.; Platnieks, I. [Association EURATOM/University of Latvia, Institute of Physics, 32 Miera Str., Salaspils, LV-2169 (Latvia)

2006-12-04

342

First Results of the Testing of the Liquid Gallium Jet Limiter Concept for ISTTOK  

NASA Astrophysics Data System (ADS)

The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages to the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaustion from fusion devices. Presently the most promising materials are Lithium and Gallium. ISTTOK, a small size tokamak, will be used to test the behavior of a liquid Gallium jet in the vacuum chamber and its influence on the plasma. This paper presents a description of the conceived setup as well as experimental results. The liquid Gallium jet is generated by hydrostatic pressure and injected in a radial position close to a moveable stainless steel limiter. Both the jet and the limiter positions are variable allowing for a controlled exposure of the liquid Gallium to the edge plasma. The main components of the Gallium loop are a MHD pump, the liquid metal injector and a filtering system. The MHD pump is of the induction type, based on rotating permanent magnets. The injector is build from a ¼? stainless steel pipe ended by a shaping nozzle. A setup has been developed to introduce oxide-free Gallium inside the loop's main supply tank. Raw liquid metal is placed inside a chamber heated and degassed under high vacuum while clean Gallium is extracted from the main body of the liquefied metal. Prior to installation on the tokamak, the experimental rig has been implemented using a Pyrex tube as test chamber to investigate the stability of the Gallium jet and its break-up length for several nozzle sizes. Results are presented in this paper. This rig was also useful to assess the behavior of the overall implemented apparatus.

Gomes, R. B.; Fernandes, H.; Silva, C.; Borba, D.; Carvalho, B.; Varandas, C.; Lielausis, O.; Klyukin, A.; Platacis, E.; Mikelsons, A.; Platnieks, I.

2006-12-01

343

Synthesis of p-Type Gallium Nitride Nanowires for Electronic and Photonic Nanodevices  

Microsoft Academic Search

Magnesium-doped gallium nitride nanowires have been synthesized via metal-catalyzed chemical vapor deposition. Nanowires prepared on c-plane sapphire substrates were found to grow normal to the substrate, and transmission electron microscopy studies demonstrated that the nanowires had single-crystal structures with a ?0001? growth axis that is consistent with substrate epitaxy. Individual magnesium-doped gallium nitride nanowires configured as field-effect transistors exhibited systematic

Zhaohui Zhong; Fang Qian; Deli Wang; Charles M. Lieber

2003-01-01

344

Gallium nitrate inhibits calcium resorption from bone and is effective treatment for cancer-related hypercalcemia  

Microsoft Academic Search

Approximately two-thirds of patients who receive the anticancer drug gallium nitrate develop mild hypocalcemia. To evaluate the mechanism of drug-induced hypocalcemia, we tested the effects of gallium nitrate upon in vitro release of ⁴⁵Ca++ from explanted fetal rat bones. The drug significantly inhibited ⁴⁵Ca++ release in response to stimulation with both parathyroid hormone and a lymphokine preparation with osteoclast activating

R. P. Jr. Warrell; R. S. Bockman; C. J. Coonley; M. Isaacs; H. Staszewski

1984-01-01

345

Transparent ring oscillator based on indium gallium oxide thin-film transistors  

Microsoft Academic Search

Highly transparent ring oscillators, exhibiting ?75% optical transmittance in the visible portion of the electromagnetic spectrum, are fabricated using indium gallium oxide as the active channel material and standard photolithography techniques. The n-channel indium gallium oxide transparent thin-film transistors (TTFTs) exhibit a peak incremental mobility of ?7cm2V?1s?1 and turn-on voltage of ?2V. A five-stage ring oscillator circuit (which does not

R. E. Presley; D. Hong; H. Q. Chiang; C. M. Hung; R. L. Hoffman; J. F. Wager

2006-01-01

346

Alloy softening in binary molybdenum alloys  

NASA Technical Reports Server (NTRS)

An investigation was conducted to determine the effects of alloy additions of Hf, Ta, W, Re, Os, Ir, and Pt on the hardness of Mo. Special emphasis was placed on alloy softening in these binary Mo alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to Mo, while those elements having an equal number or fewer s+d electrons than Mo failed to produce alloy softening. Alloy softening and hardening can be correlated with the difference in number of s+d electrons of the solute element and Mo.

Stephens, J. R.; Witzke, W. R.

1972-01-01

347

Study of liquid gallium at high pressure using synchrotron x-ray  

SciTech Connect

Liquid gallium has been studied at high pressure up to 2 GPa and ambient temperature in a diamond anvil cell using high energy synchrotron x-ray beam. The total x-ray scattering data of liquid gallium were collected up to Q = 12 A{sup -1} and analyzed using pair distribution functions (PDF). The results indicate that the first nearest neighbor peak and second nearest neighbor (shoulder) peak of PDF in liquid gallium does not change with pressure, whereas the higher order (i.e., third and fourth) nearest neighbor peaks shift towards shorter distance with increasing pressure. Reverse Monte Carlo modeling based on the observed data shows that the coordination number in the liquid gallium increases with pressure from 10.5 at 0.3 GPa to 11.6 at 2 GPa. An atomic arrangement similar to the crystalline phase of Ga(II) with coordination number of 12 is proposed for the locally dense-packed rigid unit in liquid gallium. The volume compression data derived from the structure modeling yield a bulk modulus of 12.1(6) GPa for liquid gallium.

Yu, Tony; Guo Quanzhong; Parise, John [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); Chen Jiuhua [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); Department of Mechanical and Materials Engineering, Center for the Study of Matters at Extreme Conditions, Florida International University, Miami, Florida 33199 (United States); Ehm, Lars [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States); Huang Shu [Department of Mechanical and Materials Engineering, Center for the Study of Matters at Extreme Conditions, Florida International University, Miami, Florida 33199 (United States); Luo Shengnian [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2012-06-01

348

Results from the Soviet-American gallium experiment  

SciTech Connect

A radiochemical {sup 71}Ga-{sup 71}Ge experiment to determine the primary flux of neutrinos from the Sun has begun operation at the Baksan Neutrino Observatory. The number of {sup 71}Ge atoms extracted from thirty tons of gallium was measured in five runs during the period of January to July 1990. Assuming that the extraction efficiency for {sup 71}Ge atoms produced by solar neutrinos is the same as from natural Ge carrier, we observed the capture rate to be 20 + 15/{minus}20 (stat) {plus minus} 32 (syst) SNU, resulting in a limit of less than 79 SNU (90% CL). This is to be compared with 132 SNU predicted by the Standard Solar Model.

Abazov, A.I.; Anosov, O.L.; Faizov, E.L.; Gavrin, V.N.; Kalikhov, A.V.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentseva, S.A.; Mirmov, I.N.; Ostrinsky, A.V.; Pshukov, A.M.; Revzin, N.E.; Shikhin, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Zatsepin, G.T. (AN SSSR, Moscow (USSR). Inst. Yadernykh Issledovanij); Bowles, T.J.; Cleveland, B.T.; Elliott, S.R.; O'Brien, H.A.; Wark, D.L.; Wilkerson, J.F.

1991-01-01

349

Results from the Soviet-American gallium experiment  

SciTech Connect

A radiochemical {sup 71}Ga-{sup 71}Ge experiment to determine the primary flux of neutrinos from the Sun has begun operation at the Baksan Neutrino Observatory. The number of {sup 71}Ge atoms extracted from thirty tons of gallium was measured in five runs during the period of January to July 1990. Assuming that the extraction efficiency for {sup 71}Ge atoms produced by solar neutrinos is the same as from natural Ge carrier, we observed the capture rate to be 20 + 15/{minus}20 (stat) {plus_minus} 32 (syst) SNU, resulting in a limit of less than 79 SNU (90% CL). This is to be compared with 132 SNU predicted by the Standard Solar Model.

Abazov, A.I.; Anosov, O.L.; Faizov, E.L.; Gavrin, V.N.; Kalikhov, A.V.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentseva, S.A.; Mirmov, I.N.; Ostrinsky, A.V.; Pshukov, A.M.; Revzin, N.E.; Shikhin, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Zatsepin, G.T. [AN SSSR, Moscow (USSR). Inst. Yadernykh Issledovanij; Bowles, T.J.; Cleveland, B.T.; Elliott, S.R.; O`Brien, H.A.; Wark, D.L.; Wilkerson, J.F. [Los Alamos National Lab., NM (United States); Davis, R. Jr.; Lande, K. [Pennsylvania Univ., Philadelphia, PA (United States); Cherry, M.L. [Louisiana State Univ., Baton Rouge, LA (United States); Kouzes, R.T. [Princeton Univ., NJ (United States)

1991-12-31

350

Transient Diffusion of Beryllium and Silicon in Gallium Arsenide  

NASA Astrophysics Data System (ADS)

Transient diffusion is an increasingly important phenomenon as thermal budgets for real processes decrease and diffusion during sample growth becomes more important. To fully characterize dopant diffusion in gallium arsenide, an understanding must be developed of the dominant atomistic processes for a given dopant, as well as the sources of transient effects under a given set of experimental conditions. Theoretical, experimental, and simulation results were obtained to understand transient diffusivities of beryllium and silicon in grown-in and implanted samples. In implanted samples, by understanding implant damage and modeling the evolution of point defect populations, the observed transient effects can be explained. Such phenomena cannot account for the time-dependent diffusivity observed when the dopant is introduced during molecular beam epitaxial growth. Transient diffusivities for grown-in beryllium were investigated and explained by modeling the evolution of point defect populations as they increase beyond their equilibrium levels at the growth temperature to achieve equilibrium at the anneal temperature.

Haddara, Yaser M.; Bravman, John C.

1998-08-01

351

Compilation of gallium resource data for bauxite deposits  

USGS Publications Warehouse

Gallium (Ga) concentrations for bauxite deposits worldwide have been compiled from the literature to provide a basis for research regarding the occurrence and distribution of Ga worldwide, as well as between types of bauxite deposits. In addition, this report is an attempt to bring together reported Ga concentration data into one database to supplement ongoing U.S. Geological Survey studies of critical mineral resources. The compilation of Ga data consists of location, deposit size, bauxite type and host rock, development status, major oxide data, trace element (Ga) data and analytical method(s) used to derive the data, and tonnage values for deposits within bauxite provinces and districts worldwide. The range in Ga concentrations for bauxite deposits worldwide is

Schulte, Ruth F.; Foley, Nora K.

2014-01-01

352

Experimental study on SPDT machining of Gallium Phosphide  

NASA Astrophysics Data System (ADS)

Gallium Phosphide (GaP) is widely used semiconductor material, but can be also used as a material for visible and infrared optical elements. Combination of its optical and mechanical properties such as high mechanical durability, transparency from visible to infrared wavelengths and high refractive index makes it very interesting material for design of high performance optical systems in NIR and MWIR. Manufacturing of optical elements for such wavelength ranges is shifting from traditional grinding and polishing techniques to a more versatile SPDT machining. It is therefore useful to employ SPDT in production of optical surfaces on GaP. As the GaP is similar to GaAs, but harder and more brittle, all all the problems already known for GaAs are present. Here we report results of experiments with SPDT machining of optical surfaces on GaP substrates and comparison with classical machining methods.

Vaclavík, J.; Dole?ek, R.; Lédl, V.; Psota, P.

2013-09-01

353

Multicomponental fluorimetric determination of aluminium, gallium and indium.  

PubMed

For the fast characteristics of mixtures of Aluminium, Gallium and Indium the fluorimetric evaluation in the form of complexes with 8-Hydroxyquinoline-5-sulphonic acid is described at selected pH. The highly collinear correlated fluorescent spectra and their first derivation were evaluated under various experimental conditions with the Multiple Linear Regression (MLR), Partial Least Squares (PLS) methods and Kalman filtering. When comparing the results, the PLS gives the least relative prediction errors under optimal conditions, 5.6-15.9% for the concentration range of Al 0.025-0.2 microg cm(-3), Ga 0.1-0.8 microgcm(-3) and In 0.1-0.8 microg cm(-3) in the mixture. PMID:18080828

Vojta, Simon; Jancár, Ludek; Sommer, Lumír

2008-03-01

354

Electrical and mechanical properties of vapour grown gallium monotelluride crystals  

NASA Astrophysics Data System (ADS)

The physical vapour deposition (PVD) of gallium monotelluride (GaTe) in different crystalline habits was established in the growth ampoule, strongly depending on the temperature gradient. Proper control on the temperatures of source and growth zones in an indigenously fabricated dual zone furnace could yield the crystals in the form of whiskers and spherulites. Optical and electron microscopic images were examined to predict the growth mechanism of morphologies. The structural parameters of the grown spherulites were determined by X-ray powder diffraction (XRD). The stoichiometric composition of these crystals was confirmed using energy dispersive analysis by X-rays (EDAX). The type and nature of electrical conductivity were identified by the conventional hot probe and two probe methods, respectively. The mechanical parameters, such as Vickers microhardness, work hardening index, and yield strength, were deduced from microindentation measurements. The results show that the vapour grown p-GaTe crystals exhibit novel physical properties, which make them suitable for device applications.

Reshmi, P. M.; Kunjomana, A. G.; Chandrasekharan, K. A.

2013-10-01

355

Epitaxial gallium arsenide for nuclear radiation detector applications  

NASA Astrophysics Data System (ADS)

Radiation detectors consisting of MBE-, LPE-, and MOCVD-grown gallium arsenide layers were fabricated by employing standard photolithography techniques. The active region of the devices varied between 5 and 60 ?m thickness. Hall and CV measurements confirm the high quality of the material with unintended residual doping densities of the order 10 14/ cm3 and mobilities typical for GaAs. Dark current densities as low as j D = 0.2..2.0 ?A/ cm 2 were achieved for all devices. The energy resolution (FWHM) at room temperature for 60 keV ?-photons was 1.8 keV, while for 5.8 MeV?-particles ( 244Cm ) an energy resolution of 18.3 keV (FWHM) has been determined. The detectors exhibit a charge collection efficiency of approximately 100% within the experimental error.

Lauter, J.; Bauser, E.; Förster, A.; Hardtdegen, H.; Hollfelder, M.; Lüth, H.; Protic, D.; Zehender, S.

1995-11-01

356

A pharmacokinetic and phase II study of gallium nitrate in patients with non-small cell lung cancer  

Microsoft Academic Search

This study investigated the pharmacokinetics and activity of gallium nitrate in non-small cell lung cancer when 700?mg\\/m2 was given as a 30-min infusion with prehydration every 2 weeks. Gallium was measured in plasma and urine using flameless\\u000a atomic absorption spectrophotometry, and pharmacokinetics of total and ultrafilterable gallium were calculated. Twenty-five\\u000a patients with non-small cell lung cancer received 1–12 (median 2)

Lorraine K. Webster; Ian N. Olver; Kerrie H. Stokes; Robert G. Sephton; Brian L. Hillcoat; James F. Bishop

2000-01-01

357

Etude du dopage de l'arsniure de gallium par la technique d'pitaxie en phase vapeur aux organomtalliques  

E-print Network

405 Etude du dopage de l'arséniure de gallium par la technique d'épitaxie en phase vapeur aux 14 avril 1982) Résumé. 2014 Des couches d'arséniure de gallium épitaxiées par la technique de. Abstract. 2014 The doping of gallium arsenide layers grown by the trimethylgallium/arsine method has been

Paris-Sud XI, Université de

358

CARTS A LA LOI D'OHM PRSENTS PAR DES COUCHES MINCES D'ARSENIURE DE GALLIUM  

E-print Network

108 A. �CARTS A LA LOI D'OHM PR�SENT�S PAR DES COUCHES MINCES D'ARSENIURE DE GALLIUM Par S validité de la loi d'Ohm, pour des couches minces d'arséniure de gallium portées à différentes températures, for different temperatures of gallium arsenide thin films, versus applied electrical field. The validity

Boyer, Edmond

359

Study of Magnetohydrodynamic Surface Waves on Liquid Gallium  

SciTech Connect

Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field parallel to the propagation direction. When the magnetic field is weak, waves are weakly damped and the real part of the dispersion is unaffected, while in the opposite limit waves are strongly damped with shortened wavelengths. In a table-top experiment, planar MHD surface waves on liquid gallium are studied in detail in the regime of weak magnetic field and deep liquid. A non-invasive diagnostic accurately measures surface waves at multiple locations by reflecting an array of lasers off the surface onto a screen, which is recorded by an Intensified-CCD camera. The measured dispersion relation is consistent with the linear theory with a reduced surface tension likely due to surface oxidation. In excellent agreement with linear theory, it is observed that surface waves are damped only when a horizontal magnetic field is imposed parallel to the propagation direction. No damping is observed under a perpendicular magnetic field. The existence of strong wave damping even without magnetic field suggests the importance of the surface oxide layer. Implications to the liquid metal wall concept in fusion reactors, especially on the wave damping and a Rayleigh-Taylor instability when the Lorentz force is used to support liquid metal layer against gravity, are discussed.

Hantao Ji; William Fox; David Pace; H.L. Rappaport

2004-05-13

360

Gallium-68: a systematic review of its nononcological applications.  

PubMed

The increased availability of PET facilities worldwide has sparked renewed interest in the use of generator-produced tracers such as gallium-68 (Ga). Imaging with Ga provides exciting opportunities in terms of new ligand-labelling possibilities and the exploration of novel clinical applications. The aim of the study was to summarize and appraise what has been published on the clinical applications of Ga outside oncology practice. This systematic review was based on the PRISMA guidelines. Databases searched include PubMed, Medline, Scopus, Web of Science and Google Scholar. The following search strategy was used: 'Ga' OR 'Gallium' (all fields) NOT the following (title and abstract): Oncology/NET/neuroendocrine tumour/tumor/DOTATOC, DOTATATE, DOTANOC. These results were further limited to English publications, which resulted in 205 publications on PubMed. After duplicates and irrelevant articles were removed, 72 publications remained for inclusion. Only those studies in which compounds were labelled with Ga for applications other than in oncology-related indications were included. Publications in which the focus was on oncology-related applications of Ga imaging or in which the emphasis was on aspects relating to generators, radiochemistry or physics were excluded. Although a multitude of tracers have been labelled with Ga over several decades, it has not been established in routine clinical practice yet. In addition, neuroendocrine and other oncological applications have dominated the field until relatively recently following reports of applications in infection and inflammation. The majority of publications to date involve small numbers of subjects in mainly preclinical settings. Differences in methodology preclude grouping of studies to reach a clear conclusion. There is wide scope for Ga tracer application outside oncological practice, which remains greatly underutilized. Larger clinical trials are needed to validate these applications. PMID:23812409

Vorster, Mariza; Maes, Alex; Van deWiele, Christophe; Sathekge, Mike

2013-09-01

361

Molecular dynamics simulations of adhesion and nanoindentation of gallium arsenide  

NASA Astrophysics Data System (ADS)

The purpose of this dissertation is to investigate the nanoscale hardness of gallium arsenide thin films and the elastic-plastic behavior of gallium arsenide under an indenter. These investigations were carried out using molecular dynamics (MD) simulations. The simulations are based on interatomic potentials that accurately reproduce many properties of bulk GaAs. The MD simulations performed required scalable and efficient algorithms for implementation on large parallel computers. Nanoindentation simulations were performed using an ideal indenter that was held rigid during the simulation. To reduce the transient effects due to loading, the traversal of the indenter was interrupted periodically to allow the substrate to relax. Load-displacement curves were calculated and Vickers hardness and Young's modulus were computed from the curves. The damage caused by the indenter was characterized in three ways. The material deposited on the surface was compared to bulk amorphous GaAs and found to be structurally similar, indicating that the material underwent solid-state amorphization under the indenter. Analysis of energetic atoms beneath the surface suggested the presence of dislocation loops. A centrosymmetry method was applied to characterize these defects. It was found that the method used did not perform adequately in the presence of amorphized material. Pressure distributions were calculated and atomic configurations were plotted to determine if subsurface microcracking due to the indentation was present. No indication of microcracking or pore formation was found. Adhesion between the tip and substrate was also studied. The effect of the tip-surface attraction was studied for a modified Vickers indenter with a small flat surface instead of an atomically sharp tip. For indentations less than the yield point in GaAs, the bond formation between the tip and the surface led to nonelastic deformation of the surface layer, while the layers underneath the surface behaved in a purely elastic fashion. Through a series of small indenter traversals, the yield point of GaAs was determined to be 0.6 muN.

Neal, Francis Brent, Jr.

2002-01-01

362

Solar neutrino measurement with radiochemical gallium detector (GALLEX)  

NASA Astrophysics Data System (ADS)

The GALLEX experiment for the detection of solar neutrinos by means of a radiochemical gallium detector is operated by groups from Italy, France, Germany, Israel and the USA in the Gran Sasso underground laboratory (LNGS) near L'Aquila (Italy). It consists of (1) the technical scale tank made of glass fiber reinforced polyester fabric containing 101 metric tons (54 cu m) of a highly concentrated (8 moles per liter) GaCl3 solution; (2) a gas sparging system for desorption of GeCl4 which has been formed by interaction of the neutrinos with gallium according to Ga-71 + nue yields Ge-71 + e(-) and by addition of ca. 1 mg of a stable Ge isotope; (3) the absorption columns for concentration of GeCl4 into a volume of 1 l of water; (4) the laboratory scale apparatus for conversion of GeCl4 to GeH4 and mixing with the counting gas Xe; (5) the counter filling station, and (6) the low level proportional counters. Contributions of possible side reactions which have to be corrected for, e.g. by cosmic muons, fast neutrons and alpha-emitters are discussed, as well as the purification of the target solution from long-lived ( t1/2 = 271 d) cosmogenic Ge-68. A first preliminary result after one year of solar neutrino measurement is presented. This constitutes the first direct measurement of the basic proton-proton fusion reaction in the core of the sun. This result, appreciably below the predictions of the standard solar model (SSM) (132 Solar Neutrino Units (SNU)) can be interpreted, together with the results of the chlori ne and KAMIOKANDE experiments either by astrophysics or by neutrino oscillations (Mikheyev-Smirnov-Wolfenstein (MSW) effect). The solar neutrino measurements are continuing and a calibration experiment with a Cr-51 source is in preparation.

von Ammon, Reinhard

1994-04-01

363

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes  

NASA Astrophysics Data System (ADS)

We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K <0). Applying voltage ? to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ?. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of ?. Based on this theory, we predict a dependency of ? on ? that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.

Wissman, J.; Finkenauer, L.; Deseri, L.; Majidi, C.

2014-10-01

364

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes  

SciTech Connect

We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K<0). Applying voltage ? to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ?. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of ?. Based on this theory, we predict a dependency of ? on ? that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.

Wissman, J., E-mail: jwissman@andrew.cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Finkenauer, L. [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Deseri, L. [DICAM, Department of Mechanical, Civil and Environmental Engineering, University of Trento, via Mesiano 77 38123 Trento (Italy); TMHRI-Department of Nanomedicine, The Methodist Hospital Research Institute, 6565 Fannin St., MS B-490 Houston, Texas 77030 (United States); Mechanics, Materials and Computing Center, CEE and ME-CIT, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Majidi, C. [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Robotics Institute and Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

2014-10-14

365

Distribution of trace levels of therapeutic gallium in bone as mapped by synchrotron x-ray microscopy.  

PubMed Central

Gallium nitrate, a drug that inhibits calcium release from bone, has been proven a safe and effective treatment for the accelerated bone resorption associated with cancer. Though bone is a target organ for gallium, the kinetics, sites, and effects of gallium accumulation in bone are not known. We have used synchrotron x-ray microscopy to map the distribution of trace levels of gallium in bone. After short-term in vivo administration of gallium nitrate to rats, trace (nanogram) amounts of gallium preferentially localized to the metabolically active regions in the metaphysis as well as the endosteal and periosteal surfaces of diaphyseal bone, regions where new bone formation and modeling were occurring. The amounts measured were well below the levels known to be cytotoxic. Iron and zinc, trace elements normally found in bone, were decreased in amount after in vivo administration of gallium. These studies represent a first step toward understanding the mechanism(s) of action of gallium in bone by suggesting the possible cellular, structural, and elemental "targets" of gallium. Images PMID:2349224

Bockman, R S; Repo, M A; Warrell, R P; Pounds, J G; Schidlovsky, G; Gordon, B M; Jones, K W

1990-01-01

366

Theoretical exploration of structural, electro-optical and magnetic properties of gallium-doped silicon carbide nanotubes  

NASA Astrophysics Data System (ADS)

The effects of gallium doping on the structural, electro-optical and magnetic properties of (8,0) silicon carbide nanotube (SiCNT) are investigated by using spin-polarized density functional theory. It is found from the calculation of the formation energies that gallium substitution for silicon atom is preferred. Our results show that gallium substitution at either single carbon or silicon atom site in SiCNT could induce spontaneous magnetization. The optical studies based on dielectric function indicate that new transition peaks and a blue shift are observed after gallium doping.

Behzad, Somayeh; Chegel, Raad; Moradian, Rostam; Shahrokhi, Masoud

2014-09-01

367

Growth and analysis of gallium arsenide-gallium antimonide single and two-phase nanoparticles  

NASA Astrophysics Data System (ADS)

When evaluating the path of phase transformations in systems with nanoscopic dimensions one often relies on bulk phase diagrams for guidance because of the lack of phase diagrams that show the effect of particle size. The GaAs-GaSb pseudo-binary alloy is chosen for study to gain insight into the size dependence of solid-solubility in a two-phase system. To this end, a study is performed using independent laser ablation of high purity targets of GaAs and GaSb. The resultant samples are analyzed by transmission electron microscopy. Experimental results indicate that GaAs-GaSb nanoparticles have been formed with compositions that lie within the miscibility gap of bulk GaAs-GaSb. An unusual nanoparticle morpohology resembling the appearance of ice cream cones has been observed in single component experiments. These particles are composed of a spherical cap of Ga in contact with a crystalline cone of either GaAs or GaSb. The cones take the projected 2-D shape of a triangle or a faceted gem. The liquid Ga is found to consistently be of spherical shape and wets to the widest corners of the cone, suggesting an energy minimum exists at that wetting condition. To explore this observation a liquid sphere is modeled as being penetrated by a solid gem. The surface energies of the solid and liquid, and interfacial energy are summed as a function of penetration depth, with the sum showing a cusped minimum at the penetration depth corresponding to the waist of the gem. The angle of contact of the liquid wetting the cone is also calculated, and Young's contact angle is found to occur when the derivative of the total energy with respect to penetration depth is zero, which can be a maximum or a minimum depending on the geometrical details. The spill-over of the meniscus across the gem corners is found to be energetically favorable when the contact angle achieves the value of the equilibrium angle; otherwise the meniscus is pinned at the corners.

Schamp, Crispin T.

368

Pulmonary gallium uptake in rats with granulomatosis induced by complete Freund adjuvant  

SciTech Connect

To investigate the mechanism of gallium-67 uptake in lung granulomatosis, we studied 13 rats in which lung granulomatosis was induced by injection of complete Freund adjuvant (CFA) and 14 controls. Gallium uptake was assessed in bronchoalveolar lavage fluid and lavaged lung. The cells responsible for gallium uptake were identified by latent image activation autoradiography. Gallium activity in both lavaged lungs and bronchoalveolar cells (BAC) was higher in CFA-treated animals than in controls (172,205 +/- 134,783 DPM versus 44,456 +/- 14,486 DPM +/- SD (p less than 0.05) and 40,083 +/- 16,350 DPM versus 9100 +/- 4114 DPM (p less than 0.05), respectively). In control rats, about two-thirds of total lung gallium was located in the interstitium, whereas in CFA-treated rats it was found in the mononuclear cells of lung granulomas. Gallium tracks were more numerous in the alveolar macrophages (AM) of CFA-treated rats than in control AM (28.4 +/- 10.0/field versus 8.4 +/- 3.8/field, p less than 0.001) but the number of tracks was proportional to the number of AM (52.4 +/- 18.7 versus 12.2 +/- 4.3, respectively; p less than 0.001). It is concluded that in rats with CFA-induced lung granulomatosis 1) pulmonary gallium uptake increases, 2) mononuclear cells are responsible for this uptake in both granulomas and AM, and 3) the increased uptake is due to the increased number of mononuclear cells.

Stanislas-Leguern, G.; Masse, R.; Jaubert, F.; Chretien, J.; Huchon, G.

1988-01-01

369

Metal alloy identifier  

DOEpatents

To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

Riley, William D. (Avondale, MD); Brown, Jr., Robert D. (Avondale, MD)

1987-01-01

370

Gallium Lighting, LLC, Accepts Inaugural Position on the Industry Advisory Board of UC-Light Center to Help Bring Wireless Data  

E-print Network

Gallium Lighting, LLC, Accepts Inaugural Position on the Industry Advisory Board of UC 10, 2011 ­Gallium Lighting, LLC, announced today it has accepted an inaugural position at the University of California, Riverside's Bourns College of Engineering. Gallium Lighting was one of the first

371

Nuclear Instruments and Methods in Physics Research A 460 (2001) 207212 Performance of semi-insulating gallium arsenide X-ray pixel  

E-print Network

-insulating gallium arsenide X-ray pixel detectors with current-integrating readout P.J. Sellina, *, G. Rossib , M are presented from tests of a semi-insulating gallium arsenide X-ray imaging detector, flip-chip bonded rights reserved. 1. Introduction We report the first results from a gallium arsenide (GaAs) X-ray imaging

Gruner, Sol M.

372

Gallium as a Possible Target Material for a Muon Collider or Neutrino Factory X. Ding, D. Cline, UCLA, Los Angeles, CA 90095, USA  

E-print Network

Gallium as a Possible Target Material for a Muon Collider or Neutrino Factory X. Ding, D. Cline consider the potential for a free-flowing gallium jet target as an option for a Muon Collider or Neutrino configuration using Gallium and Mercury as its target material. With optimization, the Hg jet has target radius

McDonald, Kirk

373

Stress-induced anisotropy of phosphorous islands on gallium arsenide Chemical Engineering Department, University of CaliforniaLos Angeles, Los Angeles,  

E-print Network

Stress-induced anisotropy of phosphorous islands on gallium arsenide C. H. Li Chemical Engineering growth of 2 4 phosphorous islands on 4 2 terraces of gallium arsenide 001 has been studied. The islands. Evidently, the island anisotropy is caused by stress imposed on the underlying gallium layer by the smaller

Li, Lian

374

Atomic layer structure of manganese atoms on wurtzite gallium nitride Abhijit Chinchore, Kangkang Wang, Wenzhi Lin, Jeongihm Pak, and Arthur R. Smitha  

E-print Network

Atomic layer structure of manganese atoms on wurtzite gallium nitride ,,0001¯... Abhijit Chinchore of Physics. DOI: 10.1063/1.3006434 Mn-doped gallium nitride GaN was proposed as a pos- sible dilute magnetic evident in Figs. 1 a and 1 b are 3 and higher- order streaks indicating gallium adatom reconstructions

375

All-Optical Phase-Change Memory in a Single Gallium Nanoparticle Bruno F. Soares, Fredrik Jonsson, and Nikolay I. Zheludev*  

E-print Network

All-Optical Phase-Change Memory in a Single Gallium Nanoparticle Bruno F. Soares, Fredrik Jonsson-logical resonatorless optical memory element with information encoded in the structural phase of a single 80 nm gallium gallium nanoparticle, with its four logical states written by optical pulses of a few pico-Joules energy

Jonsson, Fredrik

376

Biofilm formation on titanium implants counteracted by grafting gallium and silver ions.  

PubMed

Biofilm-associated infections remain the leading cause of implant failure. Thanks to its established biocompatibility and biomechanical properties, titanium has become one of the most widely used materials for bone implants. Engineered surface modifications of titanium able to thwart biofilm formation while endowing a safe anchorage to eukaryotic cells are being progressively developed. Here surfaces of disks of commercial grade 2 titanium for bone implant were grafted with gallium and silver ions by anodic spark deposition. Scanning electron microscopy of the surface morphology and energy dispersive X-ray spectroscopy were used for characterization. Gallium-grafted titanium was evaluated in comparison with silver-grafted titanium for both in vivo and in vitro antibiofilm properties and for in vitro compatibility with human primary gingival fibroblasts. Surface-modified materials showed: (i) homogeneous porous morphology, with pores of micrometric size; (ii) absence of cytotoxic effects; (iii) ability to support in vitro the adhesion and spreading of gingival fibroblasts; and (iv) antibiofilm properties. Although both silver and gallium exhibited in vitro strong antibacterial properties, in vivo gallium was significantly more effective than silver in reducing number and viability of biofilm bacteria colonies. Gallium-based treatments represent promising titanium antibiofilm coatings to develop new bone implantable devices for oral, maxillofacial, and orthopedic applications. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2014. PMID:25044610

Cochis, Andrea; Azzimonti, Barbara; Della Valle, Cinzia; Chiesa, Roberto; Arciola, Carla Renata; Rimondini, Lia

2014-07-01

377

Cleansing the colon in gallium-67 scintigraphy: a prospective comparison of regimens  

SciTech Connect

Colonic accumulation of gallium-67 frequently complicates the interpretation of gallium-67 scintigrams. Although various modes of cleansing the colon prior to scintigraphy have been suggested, there is controversy over their efficacy and none have been tested prospectively. Three hundred nine patients undergoing gallium-67 scintigraphy were randomly assigned to one of four cleansing regimens: (1) a high fiber diet (78 patients); (2) castor oil (76); (3) milk of magnesia and cascara (76); and (4) no preparation (79). Patient compliance rates for the four regimens were 17%, 32%, 36%, and 46%, respectively. After noncompliant patients were excluded, gallium-67 scintigrams were graded for colonic activity on a scale of 0-3 by three independent, experienced observers. Gallium-67 activity in the colon was significantly less after adminstration of castor oil than after no prepartion (p = 0.083). Regimen 3 did not produce significantly better results than regimen 4 (p = 0.42). A major impediment to the success of any cleansing regimen seems to be poor compliance of patients.

Novetsky, G.J.; Turner, D.A.; Ali, A.; Raynor, W.J.; Fordham, E.W.

1981-11-01

378

Cleansing the colon in gallium-67 scintigraphy: a prospective comparison of regimens  

SciTech Connect

Colonic accumulation of gallium-67 frequently complicates the interpretation of gallium-67 scintigrams. Although various modes of cleansing the colon prior to scintigraphy have been suggested, there is controversy over their efficacy and none have been tested prospectively. Three hundred nine patients undergoing gallium-67 scintigraphy were randomly assigned to one of four cleansing regimens: (1) a high fiber diet (78 patients); (2) castor oil (76); (3) milk of magnesia and cascara (76); and (4) not preparation (79). Patient compliance rates for the four regimens were 17%, 32%, 36%, and 46%, respectively. After noncompliant patients were excluded, gallium-67 scintigrams were graded for colonic activity on a scale of 0-3 by three independent, experienced observers. Gallium-67 activity in the colon was significantly less after administration of castor oil than after no preparation (p . 0.047). A high fiber diet also resulted in a substantial reduction of colonic activity when compared with no preparation; the difference, however, was not statistically significant (p . 0.083). Regimen 3 did not produce significantly better results than regimen 4 (p . 0.42). A major impediment to the success of any cleansing regimen seems to be poor compliance of patients.

Novetsky, G.J.; Turner, D.A.; Ali, A.; Raynor, W.J. Jr.; Fordham, E.W.

1981-01-01

379

(Polyfluoroaryl) fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon  

DOEpatents

The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interfere in the ethylene polymerization process, while affecting the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

2002-01-01

380

(Polyfluoroaryl) fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon  

DOEpatents

The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interfere in the ethylene polymerization process, while affecting the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

2001-01-01

381

Preparation of gallium-68 radiopharmaceuticals for positron tomography. Progress report, November 1, 1980-December 31, 1981  

SciTech Connect

Although the germanium-68 ..-->.. gallium-68 generator is probably the only source of positron-emitting radionuclides that could enable the widespread application of positron tomography, the commercially available /sup 68/Ga//sup 68/Ge generator system suffers from several major disadvantages. The most important of these is that the generator is eluted with EDTA, which forms a very strong chelate with gallium. In order to produce radiopharmaceuticals other than /sup 68/Ga-EDTA, it is first necessary to break the stable EDTA complex and remove all traces of EDTA. This procedure adds several steps and a significant amount of time to procedures for preparing /sup 68/Ga-radiopharmaceuticals. Several years ago, we developed a new generator using a solvent extraction system which produces /sup 68/Ga-oxine (8-hydroxyquinoline), a weak chelate. We have also carried out studies to compare generator systems which produce /sup 68/Ga in an ionic form. Using the gallium-68 eluted from these various generator systems, several /sup 68/Ga-labeled radiopharmaceuticals have been synthesized and tested in vitro and in vivo. In addition, attempts have been made to design and synthesize a lipophilic ligand for gallium-68. The stability of radiogallium complexed with a series of potentially lipophilic complexing agents has been studied using chromatographic techniques and in vivo distribution data. The potential of these complexing agents for altering the biodistribution of gallium radiopharmaceuticals has also been investigated.

Welch, M.J.

1981-06-01

382

Schottky Barrier Transport for Multiphase Gallium Nitride Nanowire  

NASA Astrophysics Data System (ADS)

Our group has shown that gallium nitride nanowires grown by catalyst-free vapor deposition at 850^oC have multiple internal crystalline regions that may be zinc blende or wurtzite phase. Stability is enabled by one or more totally coherent (0001)/(111) internal interfaces. Cross-section HRTEM has further demonstrated that, while the transverse nanowire profile appears triangular, it is actually made up of two or more surface orientations corresponding to the multi-phase internal regions. We present results of a transport investigation of these multiphase nanowires within a nanoFET circuit architecture, focusing on injection from the contacts into the nanowires. Experimental results demonstrated that a variety of surface state derived Schottky barriers could be present at the contact-nanowire interfaces. Transport across the Schottky barriers was modeled using a combined thermionic emission-tunnelling approach, leading to information about barrier height, carrier concentrations, and expected temperature behavior. The experimental and theoretical results indicate that with optimal design taking surface and internal structures into account, high current densities can be supported.

Hartz, Steven; Xie, Kan; Liu, Zhun; Ayres, Virginia

2013-03-01

383

Promises and failures of gallium as an antibacterial agent.  

PubMed

Gallium has a long history as a diagnostic and chemotherapeutic agent. The pharmacological properties of Ga(III) rely on chemical mimicry; when Ga(III) is exogenously supplied to living cells it can replace Fe(III) within target molecules, thereby perturbing bacterial metabolism. Ga(III)-induced metabolic distresses are dramatic in fast-growing cells, like bacterial cells. Interest in the antibacterial properties of Ga(III) has been raised by the compelling need for novel drugs to combat multidrug-resistant bacteria and by the shortage of new antibiotic candidates in the pharmaceutical pipeline. Ga(III) activity has been demonstrated, both in vitro and in animal models of infections, on several bacterial pathogens, also including intracellular and biofilm-forming bacteria. Ga(III) activity is affected by iron availability and the metabolic state of the cell, being maximal in iron-poor media and in respiring cells. Synergism between Ga(III) and antibiotics holds promise as last resort therapy for infections sustained by pandrug-resistant bacteria. PMID:24762310

Minandri, Fabrizia; Bonchi, Carlo; Frangipani, Emanuela; Imperi, Francesco; Visca, Paolo

2014-01-01

384

Radiation damage of gallium arsenide induced by reactive ion etching  

SciTech Connect

Radiation damage induced in the surface of gallium arsenide (GaAs) by reactive ion etching (RIE)is studied using physical and electrical analyses. The number of displaced Ga and As atoms observed by Rutherford backscattering spectrometry aligned spectra is 7.8 x 10/sup 15/ cm/sup -2/ and 1.3 x 10/sup 16/ cm/sup -2/ at rf power of 300 W (0.47 W/cm/sup 2/) and 500 W (0.78 W/cm/sup 2/), respectively. The barrier height of the Schottky electrode formed on the undamaged layer is 0.745 V. The height decreases with increasing rf power and reaches 0.47 V at 0.78 W/cm/sup 2/. Carrier concentration at the surface of the GaAs channel layer decreases with increasing rf power. The damage can be reduced by annealing at 400 /sup 0/C for 30 min. For instance, the barrier height at 300 W increases from 0.47 to 0.70 V, and the carrier concentration increases from 7.0 x 10/sup 16/ to 1.3 x 10/sup 17/ cm/sup -3/. However, the carrier concentration cannot recover to the same level as that of an undamaged layer with annealing at 400 /sup 0/C. The temperature conventionally employed in GaAs electrode annealing process.

Hara, T.; Suzuki, H.; Suga, A.; Terada, T.; Toyoda, N.

1987-11-15

385

Radiation damage of gallium arsenide induced by reactive ion etching  

NASA Astrophysics Data System (ADS)

Radiation damage induced in the surface of gallium arsenide (GaAs) by reactive ion etching (RIE)is studied using physical and electrical analyses. The number of displaced Ga and As atoms observed by Rutherford backscattering spectrometry aligned spectra is 7.8×1015 cm-2 and 1.3×1016 cm-2 at rf power of 300 W (0.47 W/cm2) and 500 W (0.78 W/cm2), respectively. The barrier height of the Schottky electrode formed on the undamaged layer is 0.745 V. The height decreases with increasing rf power and reaches 0.47 V at 0.78 W/cm2. Carrier concentration at the surface of the GaAs channel layer decreases with increasing rf power. The damage can be reduced by annealing at 400 °C for 30 min. For instance, the barrier height at 300 W increases from 0.47 to 0.70 V, and the carrier concentration increases from 7.0×1016 to 1.3×1017 cm-3. However, the carrier concentration cannot recover to the same level as that of an undamaged layer with annealing at 400 °C. The temperature conventionally employed in GaAs electrode annealing process.

Hara, Tohru; Suzuki, Hidenori; Suga, Akio; Terada, Toshiyuki; Toyoda, Nobuyuki

1987-11-01

386

Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits  

E-print Network

Integrated quantum photonics is a promising approach for future practical and large-scale quantum information processing technologies, with the prospect of on-chip generation, manipulation and measurement of complex quantum states of light. The gallium arsenide (GaAs) material system is a promising technology platform, and has already successfully demonstrated key components including waveguide integrated single-photon sources and integrated single-photon detectors. However, quantum circuits capable of manipulating quantum states of light have so far not been investigated in this material system. Here, we report GaAs photonic circuits for the manipulation of single-photon and two-photon states. Two-photon quantum interference with a visibility of 94.9 +/- 1.3% was observed in GaAs directional couplers. Classical and quantum interference fringes with visibilities of 98.6 +/- 1.3% and 84.4 +/- 1.5% respectively were demonstrated in Mach-Zehnder interferometers exploiting the electro-optic Pockels effect. This work paves the way for a fully integrated quantum technology platform based on the GaAs material system.

Jianwei Wang; Alberto Santamato; Pisu Jiang; Damien Bonneau; Erman Engin; Joshua W. Silverstone; Matthias Lermer; Johannes Beetz; Martin Kamp; Sven Hofling; Michael G. Tanner; Chandra M. Natarajan; Robert H. Hadfield; Sander N. Dorenbos; Val Zwiller; Jeremy L. O'Brien; Mark G. Thompson

2014-03-11

387

Investigation of a Gallium MPD Thruster with an Ablating Cathode  

NASA Technical Reports Server (NTRS)

Arc impedance, exhaust velocity, and plasma probe measurements are presented. The thruster is driven by a 50 microsecond pulse from a 6.2 milliohm pulse forming network, and gallium is supplied to the discharge by evaporation of the cathode. The arc voltage is found to vary linearly with the discharge current with an arc impedance of 6.5 milliohms. Electrostatic probes yield an exhaust velocity that is invariant with the discharge current and has a peak value of 20 kilometers per second, which is in reasonable agreement with the value (16 plus or minus 1 kilometer per second) calculated from the mass bit and discharge current data. Triple probe measurements yield on axis electron temperatures in the range of 0.8-3.8 eV, electron densities in the range of 1.6 x 10(exp 21) to 2.1 x 10(exp 22) per cubic meter, and a divergence half angle of 16 degrees. Measurements within the interelectrode region yield a peak magnetic field of 0.8 T, and the observed radial trends are consistent with an azimuthally symmetric current distribution. A cathode power balance model is coupled with an ablative heat conduction model predicting mass bit values that are within 20% of the experimental values.

Thomas, Robert E.; Burton, Rodney L.; Polzin, Kurt A.

2010-01-01

388

Electronic Effect on the Elastic Constants of Gallium Antimonide.  

NASA Astrophysics Data System (ADS)

The effect of doping on the elastic constants of Gallium Antimonide has been studied experimentally and explained on the basis of Keyes theory. The percentage changes in C', C(,44) and C'(,11) are .08%, .32% and .16% respectively at room temperature 25(DEGREES)C, between the samples with electron concentrations 1.9, 10('17) cm(' -3) and 1.3,10('18)cm,('-3). The shear and longitudinal deformation potential constants (XI)(,u) and (XI)(,d) of (111) band are estimated to be 16.6 (+OR-) 1.5 eV, and -(8.5 (+OR-) 2.5) eV. The deformation potential constant of (000) valley that is used in these calculations is -11.2 eV.('(31A)) The energy band separation (DELTA)E and the combined density of states effective mass used are .046 eV, and .28 m(,e). These values and also .074 eV, .56 m(,e), parameters used by Sagar give identical results. The earlier set is consistent with the reported values of temperature coefficient of band separation -1.7 eV/(DEGREES)K by Auvergne et. al. and low temperature band separation .095 eV(4.2(DEGREES)K) by Yep and Becker.

Garikepati, Poornanandam

1982-03-01

389

Ultra-thin film nanostructured gallium arsenide solar cells  

NASA Astrophysics Data System (ADS)

State-of-the-art III-V cells have reached the highest energy conversion efficiency among all types of solar cells. However, these cells are not applicable to widespread terrestrial solar energy system yet due to the high cost of epitaxial growth. Ultra-thin film absorbers with advanced light management is one of the most promising solutions to drive down the cost. In this paper, we present an ultra-thin film nano-window gallium arsenide (GaAs) solar cell design. This ultrathin cell consists of a nano-structured Al0.8Ga0.2As window layer on the front side to reduce the reflection and to trap the light, and a metal reflector on the back side to further increase the light path. The 300 nm thick GaAs cell with Al0.8Ga0.2As nano-window shows a broad band absorption enhancement from visible to near infrared (NIR), achieving a spectrally averaged absorption of 94% under normal incidence. In addition, this cell shows excellent angular absorption properties, achieving over 85% spectral averaged absorption at up to 60 degree off normal incidence. Meanwhile, this structure with planar junction and nano-window has solved the issue of low fill factor and low open-circuit voltage in nano-structured GaAs solar cell. A nano-window cell with a 3 ?m thick GaAs junction demonstrated an open circuit voltage of 0.9V.

Kang, Yangsen; Chen, Yusi; Huo, Yijie; Zhao, Li; Jia, Jieyang; Deng, Huiyang; Harris, James S.

2014-11-01

390

Gallium arsenide deep-level optical emitter for fibre optics.  

PubMed

Fibre-optic components fabricated on the same substrate as integrated circuits are important for future high-speed communications. One industry response has been the costly push to develop indium phosphide (InP) electronics. However, for fabrication simplicity, reliability and cost, gallium arsenide (GaAs) remains the established technology for integrated optoelectronics. Unfortunately, the GaAs bandgap wavelength (0.85 microm) is far too short for fibre optics at 1.3-1.5 microm. This has led to work on materials that have a large lattice mismatch on GaAs. Here we demonstrate the first light-emitting diode (LED) that emits at 1.5 microm fibre-optic wavelengths in GaAs using optical transitions from arsenic antisite (As(Ga)) deep levels. This is an enabling technology for fibre-optic components that are lattice-matched to GaAs integrated circuits. We present experimental results showing significant internal optical power (24 mW) and speed (in terahertz) from GaAs optical emitters using deep-level transitions. Finally, we present theory showing the ultimate limit to the efficiency-bandwidth product of semiconductor deep-level optical emitters. PMID:12738958

Pan, Janet L; McManis, Joseph E; Osadchy, Thomas; Grober, Louise; Woodall, Jerry M; Kindlmann, Peter J

2003-06-01

391

Low-temperature thermal conductivity of terbium-gallium garnet  

SciTech Connect

Thermal conductivity of paramagnetic Tb{sub 3}Ga{sub 5}O{sub 12} (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to 3.25 T. A minimum is observed in the temperature dependence {kappa}(T) of thermal conductivity at T{sub min} = 0.52 K. This and other singularities on the {kappa}(T) dependence are associated with scattering of phonons from terbium ions. The thermal conductivity at T = 5.1 K strongly depends on the magnetic field direction relative to the crystallographic axes of the crystal. Experimental data are considered using the Debye theory of thermal conductivity taking into account resonance scattering of phonons from Tb{sup 3+} ions. Analysis of the temperature and field dependences of the thermal conductivity indicates the existence of a strong spin-phonon interaction in TbGG. The low-temperature behavior of the thermal conductivity (field and angular dependences) is mainly determined by resonance scattering of phonons at the first quasi-doublet of the electron spectrum of Tb{sup 3+} ion.

Inyushkin, A. V., E-mail: inyushkin@imp.kiae.ru; Taldenkov, A. N. [Kurchatov Institute, Russian Research Centre (Russian Federation)

2010-11-15

392

Epitaxial Zinc Oxide Semiconductor Film deposited on Gallium Nitride Substrate  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) is a wide bandgap semiconductor which is very promising for making efficient electronic and optical devices. The goal of this research was to produce high quality ZnO film on gallium nitride (GaN) substrate by optimizing the substrate temperature. The GaN substrates were chemically cleaned and mounted on a ceramic heater and loaded into a vacuum deposition chamber that was pumped down to a base pressure of 3 x 10-7 Torr. The film deposition was preceded by a 30 minute thermal desorption carried in vacuum at 500 ^oC. The ZnO thin film was then sputter-deposited using an O2/Ar gas mixture onto GaN substrates heated at temperatures varying from 20 ^oC to 500 ^oC. Post-deposition annealing was done in a rapid thermal processor at 900 ^oC for 5 min in an ultrapure N2 ambient to improve the crystal quality of the films. The films were then optically characterized using photoluminescence (PL) measurement with a UV laser excitation. Our measurements reveal that ZnO films deposited on GaN substrate held at 200 ^oC gave the best film with the highest luminous intensity, with a peak energy of 3.28 eV and a full width half maximum of 87.4 nm. Results from low temperature (10 K) PL measurements and from x-ray diffraction will also be presented.

McMaster, Michael; Oder, Tom

2011-04-01

393

Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits  

E-print Network

Integrated quantum photonics is a promising approach for future practical and large-scale quantum information processing technologies, with the prospect of on-chip generation, manipulation and measurement of complex quantum states of light. The gallium arsenide (GaAs) material system is a promising technology platform, and has already successfully demonstrated key components including waveguide integrated single-photon sources and integrated single-photon detectors. However, quantum circuits capable of manipulating quantum states of light have so far not been investigated in this material system. Here, we report GaAs photonic circuits for the manipulation of single-photon and two-photon states. Two-photon quantum interference with a visibility of 94.9 +/- 1.3% was observed in GaAs directional couplers. Classical and quantum interference fringes with visibilities of 98.6 +/- 1.3% and 84.4 +/- 1.5% respectively were demonstrated in Mach-Zehnder interferometers exploiting the electro-optic Pockels effect. This w...

Wang, Jianwei; Jiang, Pisu; Bonneau, Damien; Engin, Erman; Silverstone, Joshua W; Lermer, Matthias; Beetz, Johannes; Kamp, Martin; Hofling, Sven; Tanner, Michael G; Natarajan, Chandra M; Hadfield, Robert H; Dorenbos, Sander N; Zwiller, Val; O'Brien, Jeremy L; Thompson, Mark G

2014-01-01

394

Growth and characterization of gallium arsenic nitride compound semiconductors  

NASA Astrophysics Data System (ADS)

GaN is a direct bandgap semiconductor that exists in the stable wurtzite phase (alphaGaN, Eg = 3.4eV) and in the metastable zincblende phase (betaGaN, Eg = 3.2eV). Recently, it has been shown when betaGaN is alloyed with GaAs, an unusually large bandgap bowing coefficient (5eV ˜ 20eV) develops in the GaAsN alloy. This alloy is receiving considerable interest from the fiber optic telecom industry for producing laser devices tunable in the important IR range. Due to the extremely low solubility limit of nitrogen in GaAs (10-9 mole%) however high quality alloy films have been difficult to grow. In this research, GaAsN alloy samples with nitrogen content up to 1.8% were successful grown using arsine, plasma enhanced nitrogen, and triethylgallium on (001) GaAs substrates. The films were grown by chemical beam epitaxy and characterized using transmission electron microscopy, X-ray diffraction and reciprocal space mapping. Results showed the processing parameter window for the GaAsN alloy growth occurred only when the nitrogen flux was approximately twice the arsenic flux, while keeping the group V/III ratio > 12. The film grew as GaAs when the nitrogen flux < 2x arsenic flux, or the film grew as phase segregated GaAs and GaN phases when the nitrogen flux > 2x arsenic flux. The use of different precursor also effected the film growth. A processing parameter window for GaAsN alloy did not exist when dimethyhydrazine (DMHy) and dimethylaminoarsenic (DMAAs) were used together as alternative nitrogen and arsenic sources respectively. Reflective high-energy electron diffraction was used to study the in-situ surface reaction behavior of the different precursors. A purposed model postulates the monomethylaminoarsenic species on the growth surface undergoes a beta-hydride elimination reaction leaving an adsorped H(ad) species on the surface. The H(ad) reacts with N(ad) species from the DMHy resulting in GaAs growth. When the flux of DMHy >> DMAAs, the film grew as phase segregated growth or as GaN.

Yun, Henry K.

395

Accurate quantification of radioactive materials by x-ray fluorescence : gallium in plutonium metal /.  

SciTech Connect

Two XRF specimen preparation methods were investigated for quantifying gallium in plutonium metal. Gallium in plutonium was chosen here as an example for demonstrating the efficacy of wavelength dispersive XRF for quantifying radioactive materials. The steps necessary to handle such materials safely will also be discussed. Quantification of plutonium samples by a well-established aqueous specimen preparation method resulted in relative precision and accuracy values of well less than 1%. As an alternative to the aqueous approach, a dried residue method was studied. Quantification of gallium in samples using this method resulted in relative precision and accuracy values an order of magnitude worse, but the method is faster, safer, and generates less waste than the aqueous process. The specimen preparation details and analysis results using each method will be presented here.

Worley, C. G. (Christopher G.)

2002-01-01

396

Demonstration of surface-enhanced Raman scattering by tunable, plasmonic gallium nanoparticles  

PubMed Central

Size-controlled gallium nanoparticles deposited on sapphire are explored as alternative substrates to enhance Raman spectral signatures. Gallium’s resilience following oxidation is inherently advantageous compared to silver for practical ex vacuo, non-solution applications. Ga nanoparticles are grown using a simple, molecular beam epitaxy-based fabrication protocol, and by monitoring their corresponding surface plasmon resonance energy through in situ spectroscopic ellipsometry, the nanoparticles are easily controlled for size. Raman spectroscopy performed on cresyl fast violet (CFV) deposited on substrates of differing mean nanoparticle size represents the first demonstration of enhanced Raman signals from reproducibly tunable self-assembled Ga nanoparticles. Non-optimized aggregate enhancement factors of ~80 were observed from the substrate with the smallest Ga nanoparticles for CFV dye solutions down to a dilution of 10 ppm. PMID:19655747

Wu, Pae C; Khoury, Christopher G.; Kim, Tong-Ho; Yang, Yang; Losurdo, Maria; Bianco, Giuseppe V.; Vo-Dinh, Tuan; Brown, April S.; Everitt, Henry O.

2009-01-01

397

Deposition of metallic gallium on re-crystallized ceramic material during focused ion beam milling  

SciTech Connect

We report a new kind of artifact observed in the preparation of a TEM sample of zirconia by FIB, which consists in the deposition of metallic gallium nano-dots on the TEM sample surface. High resolution TEM images showed a microstructure of fine equiaxed grains of ? 5 nm, with some of them possessing two particular characteristics: high contrast and well-defined fast Fourier transform. These grains could not be identified as any phase of zirconia but it was possible to identify them as gallium crystals in the zone axis [110]. Based on HRTEM simulations, the possible orientations between zirconia substrate and deposited gallium are discussed in terms of lattice mismatch and oxygen affinity. - Highlights: • We show a new type of artifact induced during preparation of TEM samples by FIB. • Deposition of Ga occurs due to its high affinity for oxygen. • Materials with small grain size (? 5 nm) could promote Ga deposition. • Small grain size permits the elastic accommodation of deposited Ga.

Muñoz-Tabares, J.A., E-mail: j.a.munoz.tabares@gmail.com [Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica s/n, Cd Universitaria, 04510 México DF, México (Mexico); Anglada, M. [Departament de Ciència dels Materials i Enginyeria Metallúrgica, Universitat Politècnica de Catalunya, Avda. Diagonal 647 (ETSEIB), 08028 Barcelona (Spain); Reyes-Gasga, J. [Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica s/n, Cd Universitaria, 04510 México DF, México (Mexico)

2013-12-15

398

Piecewise simulaton proton test of gallium arsenide and thin silicon solar cells  

NASA Technical Reports Server (NTRS)

Gallium Arsenide (GaAs) solar cells are viewed as a potential primary power source on certain future Earth orbiting satellites. However, the relative merits of gallium arsenide over silicon in a space radiation environment are largely unknown because a general degradation model for gallium arsenide does not exist. The results of a test simulating the proton radiation environment existing in a polar orbit and the concomitant effects on GaAs and thin silicon (Si) solar cells are presented. The objectives and methodology of the simulation test were discussed. The electrical characteristics of GaAs and Si solar cells are given in graph form. It was concluded that GaAs cells are viable for use on satellites in low Earth orbit.

Peterson, D. G.; Billets, S. A.

1984-01-01

399

Crystal chemistry and self-lubricating properties of monochalcogenides gallium selenide and tin selenide  

SciTech Connect

This paper describes the fundamentals of the crystal chemistry and self-lubricating mechanisms of two monochalcogenides; tin selenide and gallium selenide. Specifically, it enumerates their inter-atomic array and bond structure in crystalline states, and correlates this fundamental knowledge with their self-lubricating capacity. Friction tests assessing the self-lubricating performance of gallium and tin selenides were carried out on a pin-on-disk machine. Specifically, large crystalline pieces of gallium selenide and tin selenide were cut and cleaved into flat squares and subsequently rubbed against the sapphire balls. In another case, the fine powders (particle size {approx} 50--100 {mu}m) of gallium selenide and tin selenide were manually fed into the sliding interfaces of 440C pins and 440C disks. For the specific test conditions explored, it was found that the friction coefficients of the sapphire/gallium selenide and sapphire/tin selenide pairs were {approx} 0.23 and {approx} 0.35, respectively. The friction coefficients of 440C pin/440C disk test pairs with gallium selenide and tin selenide powders were on the orders of {approx} 0.22 and {approx} 0.38, respectively. For comparison, a number of parallel friction tests were performed with MoS{sub 2} powders and compacts and the results of these tests were also reported. The friction data together with the crystal-chemical knowledge and the electron microscopic evidence supported the conclusion that the lubricity and self-lubricating mechanisms of these solids are closely related to their crystal chemistry and the nature of interlayer bonding.

Erdemir, A.

1993-02-01

400

Gallium- and iodine-co-doped titanium dioxide for photocatalytic degradation of 2-chlorophenol in aqueous solution: Role of gallium  

NASA Astrophysics Data System (ADS)

Visible-light-driven TiO2-based catalysts for the degradation of pollutants have become the focus of attention. In the present work, iodine-doped titania photocatalysts (I-TiO2) were improved by doping with gallium (Ga,I-TiO2) and the resulting physicochemical properties and photocatalytic activity were investigated. The structural properties of the catalysts were determined by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis and transmission electron microscopy. We found that Ga probably enters the TiO2 framework for doping levels <0.5 mol%. A further increase in Ga content probably leads to dispersal of excess Ga on the TiO2 surface. The photocatalytic activity of Ga,I-TiO2 catalysts was evaluated using 2-chlorophenol (2-CP) as a model compound under visible and UV-vis light irradiation. The results indicate that 0.5 mol% Ga loading and calcination at 400 °C represent optimal conditions in the calcining temperature range 400-600 °C and with doping levels from 0.1% to 1 mol%. The effective enhancement of 2-CP degradation might be attributed to the formation of oxygen vacancies by Ga doping, which could decrease the recombination of electron-hole pairs.

Song, Shuang; Wang, Cheng; Hong, Fangyue; He, Zhiqiao; Cai, Qiaolan; Chen, Jianmeng

2011-02-01

401

Percolation of gallium dominates the electrical resistance of focused ion beam deposited metals  

SciTech Connect

Metal deposition through focused ion beam (FIB) based systems is thought to result in material composed of the primary metal from the metallo-organic precursor in addition to carbon, oxygen, and gallium. We determined, through electrical resistance and chemical composition measurements on a wide range of FIB deposited platinum and tungsten lines, that the gallium ion (Ga{sup +}) concentration in the metal lines plays the dominant role in controlling the electrical resistivity. Effective medium theory, based on McLachlan's formalisms, was used to describe the relationship between the Ga{sup +} concentration and the corresponding resistivity.

Faraby, H. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); DiBattista, M. [Qualcomm Technologies Incorporated, San Diego, California 92121 (United States); Bandaru, P. R., E-mail: pbandaru@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

2014-04-28

402

Patterns of gallium-67 scintigraphy in patients with acquired immunodeficiency syndrome and the AIDS related complex  

SciTech Connect

Thirty-two patients with AIDS related complex (ARC) or acquired immunodeficiency syndrome (AIDS) underwent /sup 67/Ga scans as part of their evaluation. Three patterns of /sup 67/Ga biodistribution were found: lymph node uptake alone; diffuse pulmonary uptake; normal scan. Gallium-67 scans were useful in identifying clinically occult Pneumocystis carinii pneumonia in seven of 15 patients with ARC who were asymptomatic and had normal chest radiographs. Gallium scans are a useful ancillary procedure in the evaluation of patients with ARC or AIDS.

Bitran, J.; Bekerman, C.; Weinstein, R.; Bennett, C.; Ryo, U.; Pinsky, S.

1987-07-01

403

Results of the Gallium-Clad Phase 3 and Phase 4 tasks (canceled prior to completion)  

SciTech Connect

This report summarizes the results of the Gallium-Clad interactions Phase 3 and 4 tasks. Both tasks were to involve examining the out-of-pile stability of residual gallium in short fuel rods with an imposed thermal gradient. The thermal environment was to be created by an electrical heater in the center of the fuel rod and coolant flow on the rod outer cladding. Both tasks were canceled due to difficulties with fuel pellet fabrication, delays in the preparation of the test apparatus, and changes in the Fissile Materials Disposition program budget.

Morris, R.N.

1998-08-01

404

Growth of epitaxial bismuth and gallium substituted lutetium iron garnet films by pulsed laser deposition  

SciTech Connect

Epitaxial bismuth and gallium substituted lutetium iron garnet thin films have been grown on (100) oriented gadolinium gallium garnet Gd{sub 3}Ga{sub 5}O{sub 12} substrates by pulsed laser deposition. The films have been studied using x-ray diffraction, high resolution x-ray diffraction, Rutherford backscattering spectroscopy, transmission electron microscopy, and electron diffraction. We obtained smooth films with thicknesses between 0.3 and 1.0 {mu}m showing good crystalline quality and epitaxial growth.

Leitenmeier, Stephan; Heinrich, Andreas; Lindner, Joerg K. N.; Stritzker, Bernd [Institut fuer Physik, Universitaet Augsburg, D-86135 Augsburg (Germany)

2006-04-15

405

Thermally induced porous structures in printed gallium coating to make transparent conductive film  

NASA Astrophysics Data System (ADS)

A directly printable gallium-based film with both optically transmissive and electrically conductive properties was proposed and demonstrated. The structures, electrical, and optical behaviors of the film printed on the substrate were experimentally investigated. It was disclosed that the porous structure induced inside the printed gallium film by thermal treatment is the main reason for the significant improvement of optical transmittance. A visible transmittance of 47% with a sheet resistance of 16.17 ?/sq was obtained when the thermal treatment temperature and time are maintained at 400 °C and 40 min, respectively.

Mei, Shengfu; Gao, Yunxia; Li, Haiyan; Deng, Zhongshan; Liu, Jing

2013-01-01

406

Calculation of Gallium-metal-Arsenic phase diagrams  

NASA Technical Reports Server (NTRS)

Electrical contacts and metallization to GaAs solar cells must survive at high temperatures for several minutes under specific mission scenarios. The determination of which metallizations or alloy systems that are able to withstand extreme thermal excursions with minimum degradation to solar cell performance can be predicted by properly calculated temperature constitution phase diagrams. A method for calculating a ternary diagram and its three constituent binary phase diagrams is briefly outlined and ternary phase diagrams for three Ga-As-X alloy systems are presented. Free energy functions of the liquid and solid phase are approximated by the regular solution theory. Phase diagrams calculated using this method are presented for the Ga-As-Ge and Ga-As-Ag systems.

Scofield, J. D.; Davison, J. E.; Ray, A. E.; Smith, S. R.

1991-01-01

407

Defect Studies in Low-Temperature Gallium Arsenide  

NASA Astrophysics Data System (ADS)

An extremely high concentration of excess As is found to be incorporated in GaAs grown by molecular-beam -epitaxy at low substrate temperatures (LTMBE GaAs). The excess As exists primarily as As antisite defects, As _{rm Ga}, and leads to a lesser extent of gallium vacancies, V_{ rm Ga}. The presence of gallium vacancies, V_{rm Ga}, was investigated by slow positron annihilation. Results indicate an excess concentration of V_{rm Ga} in LTMBE layers over bulk grown crystals. The dependence of the defect concentrations on doping has been studied by the intentional introduction of the shallow-level impurities silicon and beryllium. Electrical measurements show no free carriers are generated by n-type or p-type doping up to concentrations of 10^ {19} cm^{-3} with Si or Be respectively. Raman measurements of the local vibrational modes of the dopant atoms indicate the Be occupies the Ga substitutional sites but the Si atom is not substitutional. Addition of Si induces the incorporation of more As_{rm Ga} in the layer. As the As_ {rm Ga} concentration increases, the fraction the As_{rm Ga} which can be photoquenched decreases. The fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing studies show that a rapid decrease in the neutral As_{rm Ga} concentration occurs around 500^circ C. This distinct annealing stage is similar to that found in irradiation damaged and plastically deformed GaAs, as opposed to bulk grown GaAs in which As _{rm Ga}-related defects are stable up to 1100^circC. It is proposed that the lower temperature defect removal mechanism is due to the V_{rm Ga} enhanced diffusion of As_{ rm Ga} to arsenic precipitates. The concentration of V_{rm Ga} is supersaturated and also decreases during annealing. Hence, the diffusion is modelled with a time dependent diffusivity. Analysis of isothermal annealing kinetics for the removal of As _{rm Ga}-related defects gives an enthalpy of migration of 2.0 +/- 0.3 eV and 1.5 +/- 0.3 eV for the As_{rm Ga} and V_{rm Ga} respectively. The difference in enthalpy represents the difference between a Ga atom and an As atom hopping into the vacancy. The non-photoquenchable As_ {rm Ga}-related defects anneal away with an activation energy of 1.1 +/- 0.3 eV. Beryllium acceptors can be activated by annealing at 800^circC. The temperature difference between the annealing of defects and the activation of Be suggests the formation of As_{ rm Ga}-Be_{rm Ga} pairs. The Si donors can only be partially activated by annealing at 800^circ C. (Abstract shortened by UMI.).

Bliss, David Emory

408

Millimeter wave ferromagnetic resonance in gallium-substituted ?-iron oxide  

SciTech Connect

In millimeter wave frequency range, hexagonal ferrites with high uniaxial anisotropic magnetic fields are used as absorbers. These ferrites include M-type barium ferrite (BaFe{sub 12}O{sub 19}) and strontium ferrite (SrFe{sub 12}O{sub 19}), which have natural ferromagnetic resonant frequency range from 40 GHz to 60?GHz. However, the higher frequency range lacks suitable materials that support the higher frequency ferromagnetic resonance. A new series of gallium-substituted ?-iron oxides (?-Ga{sub x}Fe{sub 2?x}O{sub 3}) are synthesized which have ferromagnetic resonant frequencies appearing over the frequency range 30 GHz–150 GHz. The ?-Ga{sub x}Fe{sub 2?x}O{sub 3} is synthesized by the combination of reverse micelle and sol-gel techniques or the sol-gel method only. The particle sizes are observed to be smaller than 100 nm. In this paper, the free space magneto-optical approach has been employed to study these newly developed ?-Ga{sub x}Fe{sub 2?x}O{sub 3} particles in millimeter waves. This technique enables to obtain precise transmission spectra to determine the dielectric and magnetic properties of both isotropic and anisotropic ferrites in the millimeter wave frequency range from a single set of direct measurements. The transmittance and absorbance spectra of ?-Ga{sub x}Fe{sub 2?x}O{sub 3} are shown in this paper. Strong ferromagnetic resonances at different frequencies determined by the x parameter are found.

Chao, Liu, E-mail: liu.chao@tufts.edu; Afsar, Mohammed N. [Department of Electrical and Computer Engineering, Tufts University, Medford, Massachusetts 02155 (United States); Ohkoshi, Shin-ichi [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2014-05-07

409

Supersonic jet epitaxy of gallium nitride using triethylgallium and ammonia  

NASA Astrophysics Data System (ADS)

Gallium nitride (GaN) films were grown on GaN(0001)/AlN/6H-SiC composite substrates at 700-780 °C by supersonic jet epitaxy using triethylgallium (TEG) and NH3. TEG was seeded in He and N2 supersonic free jets to obtain kinetic energies of ~2.1 and ~0.5 eV, respectively, and NH3 was supplied from a variable leak valve. Higher TEG beam intensities (by about a factor of 5) were obtained by seeding in He. In situ reflection high-energy electron diffraction indicated a transition from three-dimensional to two-dimensional (2D) growth between 730 and 750 °C for films grown using TEG seeded in He and a constant NH3/TEG flux ratio. Ex situ atomic force microscopy of films grown at 730 and 750 °C revealed smooth surfaces comprised of quasi-2D islands with irregular perimeters. Cross-sectional transmission electron microscopy evidenced that the film grown at 750 °C was homoepitaxial ?-GaN with a high density of planar lattice defects. Secondary ion mass spectrometry detected high residual carbon concentrations in the films. The GaN growth rate at 750 °C was found to depend on TEG flux and NH3 pressure in a manner consistent with Langmuir-Hinshelwood kinetics. Films grown under NH3-rich conditions were faceted and microscopically rough, whereas nonfaceted, basal-plane growth was observed under Ga-rich conditions. The first-order dependence of growth rate on TEG flux under NH3-rich conditions was used to estimate Ga incorporation efficiencies for high- and low-energy TEG beams. The Ga incorporation efficiency is lower for high-energy TEG beams, consistent with a decrease in the sticking coefficient for dissociative chemisorption.

McGinnis, Arthur J.; Thomson, Darren; Banks, Andrew; Preble, Edward; Davis, Robert F.; Lamb, H. Henry

2003-01-01

410

Indium Phosphide Window Layers for Indium Gallium Arsenide Solar Cells  

NASA Technical Reports Server (NTRS)

Window layers help in reducing the surface recombination at the emitter surface of the solar cells resulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (In(x)Ga(1-x)As) and related materials based solar cells are quite promising for photovoltaic and thermophotovoltaic applications. The flexibility of the change in the bandgap energy and the growth of InGaAs on different substrates make this material very attractive for multi-bandgap energy, multi-junction solar cell approaches. The high efficiency and better radiation performance of the solar cell structures based on InGaAs make them suitable for space power applications. This work investigates the suitability of indium phosphide (InP) window layers for lattice-matched In(0.53)Ga(0.47)As (bandgap energy 0.74 eV) solar cells. We present the first data on the effects of the p-type InP window layer on p-on-n lattice-matched InGaAs solar cells. The modeled quantum efficiency results show a significant improvement in the blue region with the InP window. The bare InGaAs solar cell performance suffers due to high surface recombination velocity (10(exp 7) cm/s). The large band discontinuity at the InP/InGaAs heterojunction offers a great potential barrier to minority carriers. The calculated results demonstrate that the InP window layer effectively passivates the solar cell front surface, hence resulting in reduced surface recombination and therefore, significantly improving the performance of the InGaAs solar cell.

Jain, Raj K.

2005-01-01

411

Synthesis and characterisation of chromium lutetium gallium garnet solid solution  

SciTech Connect

The chromium lutetium gallium garnet system has been studied. Samples with 2xCaOxCr{sub 2}O{sub 3}(3 - 2x)Lu{sub 2}O{sub 3}5Ga{sub 2}O{sub 3} (x = 0.025, 0.05, 0.075, 0.1, 0.2 and 0.3,) and xCr{sub 2}O{sub 3}(3 - x)Lu{sub 2}O{sub 3}5Ga{sub 2}O{sub 3} (x = 0, 0.05, 0.075 and 0.3) compositions have been prepared in Ca,Cr:LGG and Cr:LGG systems, respectively. Samples were prepared by ceramic method, fired at 1250 deg. C/6 h and characterised by XRD, lattice parameters, UV-vis-NIR spectroscopy, CIE L * a * b * measurements and SEM/EDX. Results indicate that Ca,Cr:LGG and Cr:LGG solid solutions are obtained. In Cr:LGG system only Cr(III) is stabilised in octahedral positions substituting for Lu(III) and Ga(III). Both Cr(III) and Cr(IV) are present in Ca,Cr:LGG. The calcium is a charge compensator to stabilise Cr(IV) and this is the predominant oxidation state up to x = 0.075 composition. From this composition, Cr(III) becomes more stabilised in garnet lattice. Cr(IV) occupies generally tetrahedral and dodecahedral sites substituting for Ga(III) and Lu(III), while Cr(III) is in octahedral site substituting for Ga(III)

Galindo, R. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Badenes, J.A. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain)]. E-mail: jbadenes@qio.uji.es; Llusar, M. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Tena, M.A. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Monros, G. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain)

2007-03-22

412

Asynchronous techniques for digital MESFET gallium arsenide circuits  

NASA Astrophysics Data System (ADS)

There are many applications where ultra-fast digital arithmetic circuits are required. At ultra-high speeds a considerable part of power is dissipated within a clock generation and distribution syste. At the same time, at gigahertz frequencies the clock skew becomes a factor limiting the speed of the system. This paper presents a design methodology for highly pipelined, self-timed circuits and systems suitable for multimedia applications using Gallium Arsenide MESFET as the base technology implementation of latched logic design style (PDLL, LCFL). The use of latched logic together with the absence of the global clock provides for low power dissipation while maintaining very high speed of the system. The main advantage of the latched structure is provided by the feedback which ensures that the nose margin is higher than for a simple Direct Coupled FET Logic gate. This enables to use serial connections of the E-type transistors in the pull-down section. Therefore, in GaAs latched logic it is possible to implement logic gates based on the AND function which have several control inputs and that they generate at least one control signal for handshaking. For the typical 4- phase handshaking protocol the input signals are enable and start and the required generated signal is Done. In the paper the appropriate modifications of the handshaking protocol to accommodate the properties of the latched logic GaAs circuits is presented an the inherent latching property of LCFL is exploited to eliminate latches separate from the logic blocks in the classic pipeline. Several circuit examples demonstrate the advantages of the proposed circuit techniques.

Eshraghian, Kamran; Lachowicz, Stefan W.

1999-10-01

413

Anticancer activity of dinuclear gallium(III) carboxylate complexes.  

PubMed

The reaction of 3-methoxyphenylacetic acid, 4-methoxyphenylacetic acid, mesitylthioacetic acid, 2,5-dimethyl-3-furoic acid and 1,4-benzodioxane-6-carboxylic acid with trimethylgallium (1:1) yielded the dimeric complexes [Me(2)Ga(micro-O(2)CCH(2)C(6)H(4)-3-OMe)](2) (1), [Me(2)Ga(micro-O(2)CCH(2)C(6)H(4)-4-OMe)](2) (2), [Me(2)Ga(micro-O(2)CCH(2)SMes)](2) (3) (Mes=2,4,6-Me(3)C(6)H(2)), [Me(2)Ga{micro-O(2)C(Fur)}](2) (4) (Fur=2,5-dimethylfuran) and [Me(2)Ga{micro-O(2)C(Bdo)}](2) (5) (Bdo=1,4-benzodioxane) respectively. The molecular structure of 5 was determined by X-ray diffraction studies. The cytotoxic activity of the gallium(III) complexes (1-5) was tested against human tumor cell lines 8505C anaplastic thyroid cancer, A253 head and neck tumor, A549 lung carcinoma, A2780 ovarian cancer, DLD-1 colon carcinoma and compared with that of cisplatin. Taking into account the standard deviation, there is no significant difference in the activity for any of the compounds in any cell line. However, complex 5 presents the best IC(50) value against A253 head and neck tumor (6.6+/-0.2 microM), while complex 3 seems to be the most active against A2780 ovarian cancer (12.0+/-0.4 microM) and marginally on DLD-1 colon carcinoma (12.4+/-0.1 microM). PMID:19926362

Kaluderovi?, Milena R; Gómez-Ruiz, Santiago; Gallego, Beatriz; Hey-Hawkins, Evamarie; Paschke, Reinhard; Kaluderovi?, Goran N

2010-02-01

414

Calorizing of nickel alloys  

Microsoft Academic Search

1.Calorizing of the ÉI867, ÉI929, and ZhS6K alloys at 850–1100°C for 2–8 h leads to the formation of a surface layer which considerably increases the resistance of these alloys to oxidation.2.The thickness of the layer, the incease in weight, the heat resistance, and the hardness of the three calorized alloys are the same.3.Calorizing of nickel alloys leads to an increase

V. V. Terekhova; A. G. Andreeva

1965-01-01

415

3D structures of liquid-phase GaIn alloy embedded in PDMS with freeze casting.  

PubMed

Liquid phase electronic circuits are created by freeze casting gallium-indium (GaIn) alloys, such as eutectic gallium-indium (EGaIn), and encapsulating these frozen components within an elastomer. These metal alloys are liquid at room temperature, and can be cast using either injection or a vacuum to fill a PDMS mold and placing the mold in a freezer. Once solidified, a GaIn alloy segment can be manipulated, altered, or bonded to other circuit elements. A stretchable circuit can be fabricated by placing frozen components onto an elastomer substrate, which can be either patterned or flat, and sealing with an additional layer of elastomer. Circuits produced in this fashion are soft, stretchable, and can have complex 3D channel geometries. In contrast, current fabrication techniques, including needle injection, mask deposition, and microcontact printing, are limited to 2D planar designs. Additionally, freeze casting fabrication can create closed loops, multi-terminal circuits with branching features, and large area geometries. PMID:24067934

Fassler, Andrew; Majidi, Carmel

2013-11-21

416

Properties of plutonium and its alloys for use as fast reactor fuels  

NASA Astrophysics Data System (ADS)

Early interest in metallic plutonium fuels for fast reactors led to much research on plutonium alloy systems including binary solid solutions with the addition of aluminum, gallium, or zirconium and low melting eutectic alloys with iron and nickel or cobalt. There was also interest in ternaries of these elements with plutonium and cerium. The solid solution and eutectic alloys have most unusual properties, including negative thermal expansion in some solid-solution alloys and the highest viscosity known for liquid metals in the Pu-Fe system. Although metallic fuels have many potential advantages over ceramic fuels, the early attempts were unsuccessful because these fuels suffered from high swelling rates during burn up and high smearing densities. The liquid metal fuels experienced excessive corrosion. Subsequent work on higher melting U-Pu-Zr metallic fuels was much more promising. In light of the recent rebirth of interest in fast reactors, we review some of the key properties of the early fuels and discuss the challenges presented by the ternary alloys.

Hecker, Siegfried S.; Stan, Marius

2008-12-01

417

Single-Crystal NiAl-X Alloys Tested for Hot Corrosion  

NASA Technical Reports Server (NTRS)

Single-crystal nickel aluminide (NiAl) has been investigated extensively throughout the last several years as a potential structural material in aero-gas turbine engines. The attractive features of NiAl in comparison to Ni-base superalloys include a higher melting point, lower density, higher thermal conductivity, and excellent oxidation resistance. However, NiAl suffers from a lack of ductility and fracture toughness at low temperatures and a low creep strength at high temperatures. Alloying additions of hafnium (Hf), gallium (Ga), titanium (Ti), and chromium (Cr) have each shown some benefit to the mechanical properties over that of the binary alloy. However, the collective effect of these alloying additions on the environmental resistance of NiAl-X was unclear. Hence, the present study was undertaken to examine the hot corrosion behavior of these alloys. A companion study examined the cyclic oxidation resistance of these alloys. Several single-crystal NiAl-X alloys (where X is Hf, Ti, Cr, or Ga) underwent hot corrosion testing in a Mach 0.3 burner rig at the NASA Lewis Research Center. Samples were tested for up to 300 1-hr cycles at a temperature of 900 C. It was found that increasing the Ti content from 1 to 5 at.% degraded the hot corrosion behavior. This decline in the behavior was reflected in high weight gains and large corrosion mound formation during testing (see the figures). However, the addition of 1 to 2 at.% Cr to alloys containing 4 to 5 at.% Ti appeared to greatly reduce the susceptibility of these alloys to hot corrosion attack and negated the deleterious effect of the increased Ti addition.

Nesbitt, James A.

1999-01-01

418

Influence of various factors on the accuracy of gallium-67 imaging for occult infection  

SciTech Connect

To examine whether the results and interpretation of gallium-67 citrate imaging may be adversely influenced by factors present in compromised patients, we reviewed our 1-year experience in 69 patients in intensive care units, renal transplants, and those on hemodialysis. Our results indicate that it is an inappropriate diagnostic procedure for acute pancreatitis since seven of nine had false-negative results. Using loglinear modeling and chi-square analysis we found that treatment with antiinflammatory steroids, severe liver disease, end-stage renal disease, and renal transplantation with immunosuppressive therapy did not interfere with gallium-67 uptake. Increased rate of true-negative results in patients with end-stage renal disease was due to a greater and earlier use of the test in the febrile transplant patient and in hemodialysis patients with infections not amenable to diagnosis with gallium-67 scan (transient bacteremia and bacteriuria). We conclude that gallium-67 imaging is a useful diagnostic tool that, with the exception of acute pancreatitis, has very few false-negative results.

Maderazo, E.G.; Hickingbotham, N.B.; Woronick, C.L.; Sziklas, J.J.

1988-05-01

419

Gold\\/niobium thin film metallizations for gallium arsenide devices and circuits  

Microsoft Academic Search

As the information age opens, the demand for high performance electronics is increasing exponentially. High-speed communications devices and equipment are at the heart of this expansion. Gallium arsenide field effect transistors are the building blocks for those devices. GaAs FETs provide operation at speeds more than six times that of conventional silicon devices. There is a need to develop and

Robert Henry Esser

2000-01-01

420

ELECTRON MICROPROBE AND PHOTOLUMINESCENCE ANALYSIS OF EUROPIUM-DOPED GALLIUM NITRIDE LIGHT EMITTERS  

E-print Network

ELECTRON MICROPROBE AND PHOTOLUMINESCENCE ANALYSIS OF EUROPIUM-DOPED GALLIUM NITRIDE LIGHT EMITTERSN-on-sapphire epilayers implanted with Europium ions, producing characteristic red emission lines between 540 and 680 nm with energies largely independent of the host material. For example, doping with europium, erbium and thulium

Strathclyde, University of

421

The role of gallium-67 scintigraphy in diagnosing sources of fever in ventilated patients  

Microsoft Academic Search

Objective: To evaluate the diagnostic value of gallium-67 scin- tigraphy in febrile ventilated pa- tients by correlating the findings of 67Ga scintigraphy to sources of fe- ver and pulmonary density, as de- termined by a comprehensive pro- tocolized diagnostic evaluation. Design: Prospective observational study. Patients.\\

G. U. Meduri; J. M. Belenchia; J. D. Massie; M. Eltorky; E. A. Tolley

1996-01-01

422

Role of iron-binding proteins and enhanced capillary permeability on the accumulation of gallium-67  

SciTech Connect

We studied the role of the iron-binding proteins transferrin and lactoferrin and of increased capillary permeability on the accumulation of gallium-67 in rabbits. Intramuscular injection of histamine caused accumulation of gallium-67 (injected iv as citrate), and of Tc-99m DTPA, at the im injection site. Normal saline and albumin did not. Intramuscular injection of transferrin or lactoferrin similarly caused Ga-67 uptake. No accumulation of Tc-99m DTPA was observed at the site of transferrin injection but there was a slight accumulation at the site of lactoferrin injection. Prior saturation of transferrin or lactoferrin with ferric ion abolished their effect on Ga-67 accmulation. Gallium-67, pre-bound to transferrin in vitro, did not accumulate at the site of histamine or transferrin injection, but there was a slight accumulation at the lactoferrin site. Our results suggest that either increased capillary permeability of iron-binding proteins can cause local uptake of Ga-67. Since these factors are present at sites of inflammation, they may contribute to the accumulation of gallium in inflammatory lesions.

Tzen, K.Y.; Oster, Z.H.; Wagner, H.N. Jr.; Tsan, M.F.

1980-01-01

423

Sensitivity of chest radiography, computed tomography, and gallium scanning to metastasis of lung carcinoma  

Microsoft Academic Search

To determine the efficacy of radiologic techniques in preoperative staging of the mediastinum for lung carcinoma, the authors studied 45 patients with chest films supplemented with oblique views, esophagrams, gallium scans, and computed tomograms (CT). They interpreted the studies and correlated surgical findings using a modified classification of lymph node regions. The mediastinum was positive on chest films in 14

Paul J. Friedman; David S. Feigin; Steven E. Liston; Naomi P. Alazraki; Parviz Haghighi; John A. Young; Richard M. Peters

1984-01-01

424

Gallium-catalyzed reductive chlorination of carboxylic acids with copper(II) chloride.  

PubMed

Described herein is the direct chlorination of carboxylic acids using copper(II) chloride via a gallium(III)-catalyzed reduction in the presence of a hydrosiloxane. During this reductive chlorination, the counteranions of CuCl2 functioned as a chloride source. PMID:25295703

Sakai, Norio; Nakajima, Takumi; Yoneda, Shinichiro; Konakahara, Takeo; Ogiwara, Yohei

2014-11-01

425

Electronic shell and supershell structures in gallium clusters containing up to 7000 electrons  

Microsoft Academic Search

Gallium clusters have been studied by near-threshold photoionization up to 2400 atoms. An electronic shell structure is clearly observed and may be interpreted by considering three electrons per atom. A quantum supershell corresponding to the interference between the contributions of triangular and square classical electronic orbits is obtained at about 2500 electrons. This number is considerably larger than expected from

M. Pellarin; B. Baguenard; C. Bordas; M. Broyer; J. Lermé; J. L. Vialle

1993-01-01

426

Bilateral Comparison of Mercury and Gallium Fixed-Point Cells Using Standard Platinum Resistance Thermometer  

NASA Astrophysics Data System (ADS)

The objective of project EURAMET 1127 (Bilateral comparison of triple point of mercury and melting point of gallium) in the field of thermometry is to compare realization of a triple point of mercury (-38.8344 °C) and melting point of gallium (29.7646 °C) between the Slovenian national laboratory MIRS/UL-FE/LMK and the Croatian national laboratory HMI/FSB-LPM using a long-stem 25 ? standard platinum resistance thermometer (SPRT). MIRS/UL/FE-LMK participated in a number of intercomparisons on the level of EURAMET. On the other hand, the HMI/LPM-FSB laboratory recently acquired new fixed-point cells which had to be evaluated in the process of intercomparisons. A quartz-sheathed SPRT has been selected and calibrated at HMI/LPM-FSB at the triple point of mercury, the melting point of gallium, and the water triple point. A second set of measurements was made at MIRS/UL/FE-LMK. After its return, the SPRT was again recalibrated at HMI/LPM-FSB. In the comparison, the W value of the SPRT has been used. Results of the bilateral intercomparison confirmed that the new gallium cell of the HMI/LPM-FSB has a value that is within uncertainty limits of both laboratories that participated in the exercise, while the mercury cell experienced problems. After further research, a small leakage in the mercury fixed-point cell has been found.

Bojkovski, J.; Veliki, T.; Zvizdi?, D.; Drnovšek, J.

2011-08-01

427

Skylab experiment performance evaluation manual. Appendix J: Experiment M555 gallium arsenide single crystal growth (MSFC)  

NASA Technical Reports Server (NTRS)

Analyses for Experiment M555, Gallium Arsenide Single Crystal Growth (MSFC), to be used for evaluating the performance of the Skylab corollary experiments under preflight, inflight, and post-flight conditions are presented. Experiment contingency plan workaround procedure and malfunction analyses are presented in order to assist in making the experiment operationally successful.

Byers, M. S.

1973-01-01

428

Crystal chemistry and solid lubricating properties of the monochalcogenides gallium selenide and tin selenide  

NASA Astrophysics Data System (ADS)

The interatomic array and bond structure in crystalline states of the monochalcogenides tin selenide and gallium selenide are described and correlated with their solid lubricating capacity. Friction tests assessing their solid lubricating performance were carried out on pin-on-disk machine. Specifically, large crystalline pieces of each inorganic solid were cut and cleaved into flat squares and subsequently rubbed against sapphire balls. In another case, fine powders of gallium selenide and tin selenide and tin selenide were manually fed into the sliding interfaces of 440C pins and 440C disks. For the specific test conditions explored, friction coefficients of the sapphirel gallium selenide and sapphire/tin selenide pairs were approximately 0.23 and approximately 0.35, respectively. The friction coefficients of 440C pin/440C disk test pairs with gallium selenide and tin selenide powders were approximately 0.22 and approximately 0.38, respectively. For comparison, a number of parallel friction tests were also performed with MoS2 powders and compacts, and the results of these tests are reported. The friction data, together with the crystal-chemical knowledge and electron microscopy evidence, supported the conclusion that the solid lubricating capabilities and lubrication mechanisms of these solids are closely related to their crystal chemistry and the nature of their interlayer bonding.

Erdemir, Ali

1994-07-01

429

Properties of the plane and plano-convex resonators using berlinite, gallium phosphate and langasite  

Microsoft Academic Search

In a first part, a comparison of the main piezo-electric properties of the new piezo-electric materials of crystal class 32 is made using computed and experimental results concerning the Y rotated cuts and particularly the thermally compensated cuts. The most important facts observed are the increase of the coupling coefficient from quartz, to berlinite, langasite and gallium phosphate and the

J. Detaint; J. Schwartzel; A. Zarka; B. Capelle; D. Cochet-Muchy; E. Philippot

1994-01-01

430

Study of gallium phosphate and langasite crystals and resonators by X-ray topography  

Microsoft Academic Search

The gallium phosphate (GaPO4) is, as berlinite, a close crystallographic analogue of quartz with the advantage that it has no ?-? phase transition. It was shown that this material has very attractive properties for the applications to piezoelectric devices, due to its large coupling coefficients and to the existence of compensated cuts. Furthermore, it can be used up to extremely

B. Capelle; A. Zarka; J. Detaint; J. Schwartzel; A. Ibanez; E. Philippot; J. P. Denis

1994-01-01

431

Gallium Oxide Nanoribbons and Nanosheets Z. R. Dai, Z. W. Pan, and Z. L. Wang*  

E-print Network

and flat nanosheets of Ga2O3 have been synthesized by evaporating GaN at high temperature with the presence, and thermal transport phenomena in one-dimensional objects. In addition to carbon nanotubes, wire- like. Gallium oxide is an important functional material. It has been used as insulating barrier for spin

Wang, Zhong L.

432

Measurements on Gallium Arsenide building blocks and implications for analog IC design  

Microsoft Academic Search

Gallium Arsenide technology has offered the promise of very high frequency operation but its potential has not been fully realized due to technological problems which have revealed themselves in undesirable and unpredictable device characteristics. This article presents measured DC characteristics for some current mirrors and transconductors which are believed to be important building blocks for future high-speed GaAs communication circuits.

D. G. Haigh; C. Toumazou; S. J. Newett

1991-01-01

433

Gallium/aluminum nanocomposite material for nonlinear optics and nonlinear plasmonics  

E-print Network

a substantial change in its optical properties, while the framework of aluminum domains provides the founda.9999% is placed on the exposed surface of the alumi- num. Once the oxide layer on aluminum surface beneathGallium/aluminum nanocomposite material for nonlinear optics and nonlinear plasmonics A. V

Zheludev, Nikolay

434

Gallium nitrate inhibits calcium resorption from bone and is effective treatment for cancer-related hypercalcemia  

SciTech Connect

Approximately two-thirds of patients who receive the anticancer drug gallium nitrate develop mild hypocalcemia. To evaluate the mechanism of drug-induced hypocalcemia, we tested the effects of gallium nitrate upon in vitro release of /sup 45/Ca++ from explanted fetal rat bones. The drug significantly inhibited /sup 45/Ca++ release in response to stimulation with both parathyroid hormone and a lymphokine preparation with osteoclast activating factor activity. The inhibitory effects on bone resorption were both time- and dose-dependent. Later, in a pilot study, we treated 10 patients who had cancer-related hypercalcemia with gallium nitrate administered by continuous infusion. All patients responded by a reduction of total serum calcium to normal or subnormal concentrations (13.8 +/- 1.05 mg/dl, mean +/- SD pretreatment, to 8.03 +/- 1.03 mg/dl, mean posttreatment nadir). Our results indicate that gallium nitrate effectively treats cancer-related hypercalcemia and that it probably acts by inhibiting calcium release from bone.

Warrell, R.P. Jr.; Bockman, R.S.; Coonley, C.J.; Isaacs, M.; Staszewski, H.

1984-05-01

435

Ultra-low power fiber-coupled gallium arsenide photonic crystal cavity electro-optic modulator  

E-print Network

Ultra-low power fiber-coupled gallium arsenide photonic crystal cavity electro-optic modulator Gary. Kuramochi, and M. Notomi, "Low power and fast electro-optic silicon modulator with lateral p-i-n embedded, "Low Vpp, ultralow-energy, compact, high-speed silicon electro-optic modulator," Opt. Express 17

Vuckovic, Jelena

436

Epitaxial growth of gallium nitride thin films on A-plane sapphire by molecular beam epitaxy  

E-print Network

Epitaxial growth of gallium nitride thin films on A-plane sapphire by molecular beam epitaxy DN on 112¯0 sapphire A plane . The 11¯02 cleavage plane in sapphire is shown to extend to the GaN lattice buffer is therefore necessary. A systematic study of GaN growth on the A-plane sapphire by plasma

Basu, Soumendra N.

437

Structure and optical properties of cubic gallium oxynitride synthesized by solvothermal route  

SciTech Connect

Cubic gallium oxynitride was synthesized using a solvothermal processing route. Crystal structure, chemical composition, optical properties and the influence of heat treatment in either reactive or inert atmospheres have been investigated. Despite a strongly distorted lattice revealed using X-ray diffraction, the Raman active modes of a cubic gallium oxynitride structure could be observed. With diffusive reflectance UV–Vis spectroscopy a band gap at around 4.8 eV has been observed. Additionally, cathodoluminescence spectroscopy exhibited observable luminescence caused by defect-related transitions within the optical gap. Cathodoluminescence and photoluminescence spectra collected after heat treatments showed significant changes in the defect structure. In particular, for annealing in ammonia the main spectral modifications were related to the substitution of oxygen by nitrogen on anion sites. - Graphical abstract: CL spectra of gallium oxynitride: As-prepared and heat-treated at temperatures of 500 °C in different atmospheres. Highlights: ? Raman spectrum of cubic gallium oxynitride. ? Experimental determination of optical band gap. ? Shift of band gap energy due to heat treatment. ? Nitrogen incorporation leads to deep level acceptor states. ? Red shifted luminescence spectrum.

Oberländer, Andreas, E-mail: andreas.oberlaender@ikts.fraunhofer.de [Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Winterbergstr. 28, 01277 Dresden (Germany); Kinski, Isabel [Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Winterbergstr. 28, 01277 Dresden (Germany); Zhu, Wenliang; Pezzotti, Giuseppe [Ceramic Physics Laboratory and Research Institute for Nanoscience, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8585 Kyoto (Japan); Michaelis, Alexander [Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Winterbergstr. 28, 01277 Dresden (Germany)

2013-04-15

438

Femtosecond laser ablation of gallium arsenide investigated with time-of-flight mass spectroscopy  

E-print Network

semiconductors, laser ablation near threshold can be described in terms of thermal processes even when fem is relatively high also in the range below the ablation threshold. Our results show that the non- thermallyFemtosecond laser ablation of gallium arsenide investigated with time- of-flight mass spectroscopy

von der Linde, D.

439

Gallium-induced cell death in lymphoma: role of transferrin receptor cycling, involvement of Bax and the mitochondria, and effects of proteasome inhibition.  

PubMed

Gallium nitrate is a metallodrug with clinical efficacy in non-Hodgkin's lymphoma. Its mechanisms of antineoplastic action are not fully understood. In the present study, we investigated the roles of transferrin receptor (TfR) targeting and apoptotic pathways in gallium-induced cell death. Although DoHH2 lymphoma cells displayed a 3-fold lower number of TfRs than CCRF-CEM lymphoma cells, they were 3- to 4-fold more sensitive to gallium nitrate. Despite a lower TfR expression, DoHH2 cells had greater TfR cycling and iron and gallium uptake than CCRF-CEM cells. In other lymphoma cell lines, TfR levels per se did not correlate with gallium sensitivity. Cells incubated with gallium nitrate showed morphologic changes of apoptosis, which were decreased by the caspase inhibitor Z-VAD-FMK and by a Bax-inhibitory peptide. Cells exposed to gallium nitrate released cytochrome c from mitochondria and displayed a dose-dependent increase in caspase-3 activity. An increase in active Bax levels without accompanying changes in Bcl-2 or Bcl-X(L) was seen in cells incubated with gallium nitrate. The endogenous expression of antiapoptotic Bcl-2 was greater in DoHH2 cells than in CCRF-CEM cells, suggesting that endogenous Bcl-2 levels do not correlate with cell sensitivity to gallium nitrate. Gallium-induced apoptosis was enhanced by the proteasome inhibitor bortezomib. Our results suggest that TfR function rather than TfR number is important in gallium targeting to cells and that apoptosis is triggered by gallium through the mitochondrial pathway by activating proapoptotic Bax. Our studies also suggest that the antineoplastic activity of combination gallium nitrate and bortezomib warrants further investigation. PMID:17121930

Chitambar, Christopher R; Wereley, Janine P; Matsuyama, Shigemi

2006-11-01

440

Synthesis and characterization of gallium nitride and zinc germanium nitride  

NASA Astrophysics Data System (ADS)

Activated nitrogen derived from either a constricted DC plasma source or a Delta Glow Model DG300 Radio Frequency plasma operating at 13.56 Mhz was reacted with liquid Ga in Ga/In and Ga/Sn alloys at growth temperature around 1200K in order to synthesize polycrystalline GaN. The use of activated nitrogen from a plasma source circumvents the higher pressure and temperature required in high pressure solution growth of GaN. The inert elements In and Sn in the alloy were used to enhance the nitrogen solubility in the Ga melt. Characterization was accomplished using SEM, EDAX, X-ray diffraction and photoluminescence spectroscopy. The mass of GaN crust grown in a given time decreased with increasing Ga dilution. The GaN crust grew continuously from 50% Ga Ga/Sn alloy for the first 24 hours. The photoluminescence signal from the outer surface of the GaN crust was an order of magnitude higher than the interior surface. The integrated intensity of the photoluminescence signal was directly proportional to the input laser power, whereas the photoluminescence spectral features remained unchanged with changing laser power. ZnGeN2 is a II-IV-N2 ternary semiconductor that has an optical band gap and crystal lattice structure nearly identical with GaN and may provide an alternative to GaN for optoelectronic devices; however, relatively little research has been done on its growth and properties. Polycrystalline ZnGeN2 was synthesized via vapor growth from Zn and Ge metals by thermal cracking of NH3. The crystal structure and lattice parameters were measured, and lattice defects were imaged using transmission electron microscopy. Photoluminescence spectroscopy measurements showed broad "yellow-band" impurity luminescence peak near 2.2 eV. The highest efficiency and highest energy near band edge luminescence yet observed was found for this material.

Bekele, Challa

441

Optical characterization of CuIn1?xGaxSe2 alloy thin films by spectroscopic ellipsometry  

Microsoft Academic Search

Optical constants of polycrystalline thin film CuIn1?xGaxSe2 alloys with Ga\\/(Ga+In) ratios from 0 to 1 have been determined by spectroscopic ellipsometry over an energy range of 0.75–4.6 eV. CuIn1?xGaxSe2 films were deposited by simultaneous thermal evaporation of elemental copper, indium, gallium and selenium. X-ray diffraction measurements show that the CuIn1?xGaxSe2 films are single phase. Due to their high surface roughness,

P. D. Paulson; R. W. Birkmire; W. N. Shafarman

2003-01-01

442

Optical characterization of CuIn1-xGaxSe2 alloy thin films by spectroscopic ellipsometry  

Microsoft Academic Search

Optical constants of polycrystalline thin film CuIn1-xGaxSe2 alloys with Ga\\/(Ga+In) ratios from 0 to 1 have been determined by spectroscopic ellipsometry over an energy range of 0.75-4.6 eV. CuIn1-xGaxSe2 films were deposited by simultaneous thermal evaporation of elemental copper, indium, gallium and selenium. X-ray diffraction measurements show that the CuIn1-xGaxSe2 films are single phase. Due to their high surface roughness,

P. D. Paulson; R. W. Birkmire; W. N. Shafarman

2003-01-01

443

Preconceptual design for separation of plutonium and gallium by ion exchange  

SciTech Connect

The disposition of plutonium from decommissioned nuclear weapons, by incorporation into commercial UO{sub 2}-based nuclear reactor fuel, is a viable means to reduce the potential for theft of excess plutonium. This fuel, which would be a combination of plutonium oxide and uranium oxide, is referred to as a mixed oxide (MOX). Following power generation in commercial reactors with this fuel, the remaining plutonium would become mixed with highly radioactive fission products in a spent fuel assembly. The radioactivity, complex chemical composition, and large size of this spent fuel assembly, would make theft difficult with elaborate chemical processing required for plutonium recovery. In fabricating the MOX fuel, it is important to maintain current commercial fuel purity specifications. While impurities from the weapons plutonium may or may not have a detrimental affect on the fuel fabrication or fuel/cladding performance, certifying the effect as insignificant could be more costly than purification. Two primary concerns have been raised with regard to the gallium impurity: (1) gallium vaporization during fuel sintering may adversely affect the MOX fuel fabrication process, and (2) gallium vaporization during reactor operation may adversely affect the fuel cladding performance. Consequently, processes for the separation of plutonium from gallium are currently being developed and/or designed. In particular, two separation processes are being considered: (1) a developmental, potentially lower cost and lower waste, thermal vaporization process following PuO{sub 2} powder preparation, and (2) an off-the-shelf, potentially higher cost and higher waste, aqueous-based ion exchange (IX) process. While it is planned to use the thermal vaporization process should its development prove successful, IX has been recommended as a backup process. This report presents a preconceptual design with material balances for separation of plutonium from gallium by IX.

DeMuth, S.F.

1997-09-30

444

Weldability of High Alloys  

SciTech Connect

The purpose of this study was to investigate the effect of silicon and iron on the weldability of HAYNES HR-160{reg_sign} alloy. HR-I60 alloy is a solid solution strengthened Ni-Co-Cr-Si alloy. The alloy is designed to resist corrosion in sulfidizing and other aggressive high temperature environments. Silicon is added ({approx}2.75%) to promote the formation of a protective oxide scale in environments with low oxygen activity. HR-160 alloy has found applications in waste incinerators, calciners, pulp and paper recovery boilers, coal gasification systems, and fluidized bed combustion systems. HR-160 alloy has been successfully used in a wide range of welded applications. However, the alloy can be susceptible to solidification cracking under conditions of severe restraint. A previous study by DuPont, et al. [1] showed that silicon promoted solidification cracking in the commercial alloy. In earlier work conducted at Haynes, and also from published work by DuPont et al., it was recognized that silicon segregates to the terminal liquid, creating low melting point liquid films on solidification grain boundaries. Solidification cracking has been encountered when using the alloy as a weld overlay on steel, and when joining HR-160 plate in a thickness greater than19 millimeters (0.75 inches) with matching filler metal. The effect of silicon on the weldability of HR-160 alloy has been well documented, but the effect of iron is not well understood. Prior experience at Haynes has indicated that iron may be detrimental to the solidification cracking resistance of the alloy. Iron does not segregate to the terminal solidification product in nickel-base alloys, as does silicon [2], but iron may have an indirect or interactive influence on weldability. A set of alloys covering a range of silicon and iron contents was prepared and characterized to better understand the welding metallurgy of HR-160 alloy.

Maroef, I

2003-01-22

445

Alloying of aluminum-beryllium alloys  

NASA Astrophysics Data System (ADS)

The existing phase diagrams of Al-Be- X alloys, where X is an alloying element, are analyzed. Element X is noted to poorly dissolve in both aluminum and beryllium. It is shown that the absence of intermetallic compounds in the Al-Be system affects the phase equilibria in an Al-Be- X system. Possible phase equilibria involving phases based on aluminum, beryllium, and intermetallic compounds are proposed, and the types of strengthening of Al-Be alloys by an addition of a third element are classified.

Molchanova, L. V.; Ilyushin, V. N.

2013-01-01

446

Structure-composition-property relationships in 5xxx series aluminum alloys  

NASA Astrophysics Data System (ADS)

Al-Mg alloys are well suited for marine applications due to their low density, ease of fabrication, structural durability, and most notably resistance to corrosion. The purpose of this study is to investigate the effects of alloying additions, mechanical processing and heat treatments on the development of grain boundary phases that have an effect on intergranular corrosion (IGC). Cu, Zn, and Si modified compositions of AA5083 were produced that were subjected to a low and high degree of cold work and various heat treatments. ASTM G67 (NAMLT) intergranular corrosion testing and detailed microstructural characterization for various alloys was carried out. An optimal composition and processing condition that yielded the best intergranular corrosion resistant material was identified based on the ASTM G67 test screening. Further, the outstanding modified AA5083 was selected for further microstructural analysis. This particular alloy with has a magnesium level high enough to make it susceptible to intergranular corrosion is very resistant to IGC. It was found that development of the appropriate sub-structure with some Cu, Si and Zn resulted in a material very resistant to IGC. Formation of many sinks, provided by sub-boundaries, within microstructure is very beneficial since it produces a relatively uniform distribution of Mg in the grain interiors, and this can suppress sensitization of this alloy very successfully. This is a very promising rote for the production of high-strength, and corrosion resistant aluminum alloys. Additionally in this study, TEM sample preparation become very crucial step in grain boundary phase investigation. Focus Ion Beam (FIB) milling was used as a primary TEM sample preparation technique because it enables to extract the samples from desired and very specific locations without dissolving grain boundary phases as it was in conventional electropolishing method. However, other issues specifically relevant to FIB milling of aluminum alloys related to Ga accumulation were discovered, that produce significant microstructural artifacts. It is well known that liquid gallium can cause Liquid Metal Embitterment (LME) aluminum alloys, and gallium readily penetrates aluminum grain boundaries. Low energy Ar ion nanomilling is potentially quite effective at removing gallium from the external and internal surfaces of aluminum thin foils, but can still leave persistent artifacts. Al-Mg alloys can be also susceptible to localized corrosion such as pitting corrosion in the presence of chloride ions. In this study the phases responsible for this type of corrosion were identified. ASSET (ASTM G66) test was used to determine the influence of heat-treatment on pitting corrosion on various modified AA5083 alloys. Additionally, potentiodynamic polarization as well as potentiostatic measurements in conjunction with SEM analysis were carried out to obtain pitting potential (Epit) and to determine the location of metastable pit initiation, respectively.

Unocic, Kinga A.

447

Tunable laser utilizing an electronic--vibrational transition in chromium in a gadolinium scandium gallium garnet crystal  

SciTech Connect

A laser continuously tunable in the range 766--820 nm was constructed. It utilizes an electronic--vibrational transition in chromium in a gadolinium scandium gallium garnet crystal kept at room temperature and subjected to nonselective flashlamp pumping.

Zharikov, E.V.; Il'ichev, N.N.; Kalitin, S.P.; Laptev, V.V.; Malyutin, A.A.; Osiko, V.V.; Ostroumov, V.G.; Pashinin, P.P.; Prokhorov, A.M.; Smirnov, V.A.

1983-09-01

448

Practical synthesis of aromatic nitriles via gallium-catalysed electrophilic cyanation of aromatic C-H bonds.  

PubMed

A gallium-catalysed, direct cyanation reaction of aromatic and heteroaromatic C-H bonds with cyanogen bromide was developed as a practical synthetic method for the preparation of aromatic nitriles. PMID:22344311

Okamoto, Kazuhiro; Watanabe, Masahito; Murai, Masahito; Hatano, Ryo; Ohe, Kouichi

2012-03-25

449

Structure and Properties of Epitaxial Dielectrics on gallium nitride  

NASA Astrophysics Data System (ADS)

GaN is recognized as a possible material for metal oxide semiconductor field effect transistors (MOSFETs) used in high temperature, high power and high speed electronic applications. However, high gate leakage and low device breakdown voltages limit their use in these applications. The use of high-kappa dielectrics, which have both a high permittivity (?) and high band gap energy (Eg), can reduce the leakage current density that adversely affects MOS devices. La2O3 and Sc2O 3 are rare earth oxides with a large Eg (6.18 eV and 6.3 eV respectively) and a relatively high ? (27 and 14.1 respectively), which make them good candidates for enhancing MOSFET performance. Epitaxial growth of oxides is a possible approach to reducing leakage current and Fermi level pinning related to a high density of interface states for dielectrics on compound semiconductors. In this work, La2O3 and Sc2O 3 were characterized structurally and electronically as potential epitaxial gate dielectrics for use in GaN based MOSFETs. GaN surface treatments were examined as a means for additional interface passivation and influencing subsequent oxide formation. Potassium persulfate (K2(SO4)2) and potassium hydroxide (KOH) were explored as a way to achieve improved passivation and desired surface termination for GaN films deposited on sapphire substrates by metal organic chemical vapor deposition (MOCVD). X-ray photoelectron spectroscopy (XPS) showed that KOH left a nitrogen-rich interface, while K2(SO 4)2 left a gallium-rich interface, which provides a way to control surface oxide formation. K2(SO4)2 exhibited a shift in the O1s peak indicating the formation of a gallium-rich GaOx at the surface with decreased carbon contaminants. GaO x acts as a passivating layer prior to dielectric deposition, which resulted in an order of magnitude reduction in leakage current, a reduced hysteresis window, and an overall improvement in device performance. Furthermore, K2(SO4)2 resulted in an additional 0.4 eV of upward band bending at the surface, which should be considered when determining heterojunction band offsets with GaN. Epitaxial La2O3 and Sc2O3 were successfully deposited on GaN by molecular beam epitaxy (MBE). Sc 2O3 exhibited a cubic bixbyite crystal structure, while La 2O3 had a mix of both cubic and hexagonal crystal structures. A highly defective structure was observed for La2O3, compared to Sc2O3, which results from its larger mismatch with GaN (14.5% and 8.9%, respectively). TEM images indicated an abrupt atomic interface for Sc2O3 films, but an interfacial layer was observed for La2O3 on GaN. Additionally, La 2O3 was shown to be extremely reactive with water and carbon dioxide in air, forming both hydroxides and carbonates within 15 minutes of exposure. Therefore, tantalum and silicon were investigated as in-situ capping metals to prevent these deleterious effects. XPS was utilized to determine a valence band offset (VBO) and conduction band offset of 1.9 +/- 0.1 eV and 0.9 +/- 0.1 eV for La2O 3 on GaN. Similarly, Sc2O3 had a VBO and CBO of 0.8 +/- 0.1 eV and 2.1 +/- 0.1 eV, respectively. Both oxides exhibited sufficient band offsets to prevent thermionic emission of carriers, even at high operation temperatures, making them good candidates for insulator layers in high temperature, high power applications. Preliminary C-V curves, for La2O3 and Sc2 O3 MOS capacitors, showed large charge accumulation layers, extremely high permittivity values, and low hysteresis windows indicative of low density of interface traps and fixed oxide charges. I-V curves showed a reduction in leakage current density for both oxides compared to Si 3N4, a readily used gate dielectric for GaN devices. The larger reduction achieved with La2O3 films is attributed to a passivating interfacial layer that minimizes the amount of dislocations propagating into the oxide. These preliminary results point to the viability of these gate oxides in GaN MOSFET devices.

Wheeler, Virginia Danielle

450

Epitaxial gallium phosphide on silicon (111) from the liquid phase for solar cell applications  

NASA Astrophysics Data System (ADS)

Multijunction structures composed of III-V materials grown on a III-V or Ge substrate are often employed to achieve high solar cell conversion efficiencies. However, it is advantageous to consider alternate substrates that can lower cost, such as the well developed Si, as a platform on which multi-junction solar structures can be grown. Growth of III-Vs on an alternate substrate such as Si requires careful consideration of the lattice constant mismatch as this will greatly influence the physical and electronic quality of the film. A material that is closely lattice matched with Si is Gallium phosphide (GaP). This lattice matching allows for good quality epitaxial growth and GaP can be alloyed with other III-V materials to tune the bandgap, which is an important property for multi-junction solar cells. In this work, liquid phase epitaxy (LPE) was used to grow GaP films on miscut and aligned Si (111) substrates. The films have been characterized by SEM and XRD to show that the GaP films are planar with uniform morphology and good crystal quality. The composition has been found by XPS and Auger spectroscopy to be GaP with 10-20% Si content. High resolution XRD analysis confirmed that the films are epitaxial and have a threading dislocation density of 2 x 106 cm-2 for growth on aligned Si (111) which is promising for the development of III-V/Si multi-junction solar cells. A four junction solar cell stack that includes a Si junction has a theoretical efficiency greater than 50%. In this structure, a GaP layer can act as a buffer layer on Si to growth other III-V materials with optimized bandgaps. Therefore, the effect of a GaP film on a Si solar cell was investigated. The results of this investigation show that growing a GaP layer on a Si solar cell fabricated by a diffusion process increases the series resistance and has lower Voc. Quantum efficiency measurements show that there is some reduction in efficiency of collection of carriers excited by wavelengths shorter than 450 nm which could be due to absorption in the GaP layer and recombination at the interface. A GaP layer grown on a p-type Si substrate exhibited similar current voltage characteristics as the GaP layer grown on a Si solar cell. SIMS depth profiling showed that phosphorus diffusion occurs during growth of GaP, creating a n-type doped. This indicates that a GaP layer can be grown on a Si substrate to directly make a solar cell. Epitaxial GaP layers have been grown on Si (111) substrates with high crystal quality which is promising for use as a buffer layer. Growth of GaP on Si can be used to directly fabricate a Si solar cell. This GaP/Si structure will be beneficial to solar cell and many other optoelectronic applications.

Huang, Susan R.

451

Therapeutic Effect of Organic Gallium on Ovariectomized Osteopenic Rats by Decreased Serum Minerals and Increased Bone Mineral Content  

Microsoft Academic Search

The purpose of this study was to verify the effect of organic gallium on ovariectomized osteopenic rats. Thirty Wistar female\\u000a rats used were divided into three groups: (1) sham-operation rats (control), (2) ovariectomized (OVX) rats with osteopenia,\\u000a and (3) OVX rats with osteopenia treated with organic gallium. Treatments were performed over an 8-week period. At sacrifice,\\u000a the fifth lumbar vertebral

Zhaoji Ma; Qin Fu

2010-01-01

452

Magnetization and FMR studies of crystal-ion-sliced narrow linewidth gallium-doped yttrium iron garnet  

Microsoft Academic Search

Recent interest in employing single-crystal yttrium iron garnet (YIG) films for miniaturized microwave integrated circuit applications has prompted us to study detaching liquid phase epitaxy (LPE) grown YIG films from their gadolinium gallium garnet (GGG) substrates via crystal ion slicing (CIS). We report studies of magnetization and ferromagnetic resonance (FMR) of narrow linewidth gallium-doped YIG (GaYIG) films in various stages

F. J. Rachford; M. Levy; R. M. Osgood; A. Kumar; H. Bakhru

2000-01-01

453

Growth kinetics and investigations of spontaneous formation of superlattices in AlGaN alloys  

NASA Astrophysics Data System (ADS)

GaN and its alloys with AlN constitute a very important class of materials with a broad range of potential applications in ultraviolet optoelectronic devices, high frequency, high temperature and high power electronic devices and sensors based on micro-electromechanical devices. This work addresses the kinetics of growth of AlGaN alloys by molecular beam epitaxy and the study of spontaneous formation of superlattices of various periodicities. High quality films were grown epitaxially by plasma assisted MBE on sapphire substrates employing appropriate buffer layers. The nature of the buffer layer was found to control the polarity of the films. The ratio of the group-III to group-V atomic fluxes during growth was found to control the adatom surface diffusion and the incorporation of Ga atoms, as well as the film's structural and optical properties. Films grown under nitrogen rich conditions show a rough morphology due to reduced surface diffusion, while films grown under group-III rich conditions are atomically smooth. The growth kinetics of the AlGaN films were investigated at the substrate temperature range of 750 to 800°C and found to be drastically different than in the case of traditional III-V compounds. The sticking probability of aluminum atoms is unity while the sticking probability of gallium is constant only under nitrogen rich growth conditions. In the group-III rich growth regime the sticking probability of gallium decreases monotonically with group-III fluxes since the available active nitrogen bonds preferentially to Al. The spontaneous formation of superlattices in the films during growth was investigated. The formation of superlattices with period of two monolayers was found to be promoted by nitrogen rich conditions of growth on nitrogen polar surfaces. Furthermore, superlattices with longer periods (seven and twelve monolayers) were observed in films grown on gallium polar surfaces. The optical properties of the GaN and AlGaN films were investigated by transmission, luminescence and photoconductivity measurements in the entire alloy composition. A reduction in the direct bandgap of the alloys was correlated with the presence of long range atomic order of group-III atoms.

Iliopoulos, Eleftherios

454

Yeast-incorporated gallium promotes fracture healing by increasing callus bony area and improving trabecular microstructure on ovariectomized osteopenic rats.  

PubMed

The purpose of this study was to analyze the impact of yeast-incorporated gallium on fracture healing in ovariectomized osteopenic rats. Forty Wistar female rats used were divided into three groups: sham-operated rats (SHAM), ovariectomized (OVX) rats, and ovx rats treated with yeast-bound gallium (YG). A standardized fracture-healing model with stable plate fixation was established for rat femoral. After 4-week stable fixation, animals were killed to prepare bones for Micro-CT, biomechanical testing, and histomorphometry. In addition, bone samples were obtained to evaluate the content of mineral substances in bones. Quantitative analysis of the bones from animals in the organic gallium group revealed significantly increased mineral contents compared to bones from OVX and SHAM groups. Micro-CT showed that treatment with yeast-incorporated gallium increased BV/TV and trabecular thickness and decreased trabecular separation in ovx animals. Histomorphometric evaluation demonstrated that YG increased callus area and callus bone formation. Yeast-bound gallium also improved the biomechanical properties of bone healing. In conclusion, this study suggests that yeast-incorporated gallium could promote fracture healing in ovariectomized rats. PMID:20446054

Pei, Yi; Fu, Qin

2011-06-01

455

First-principles melting of gallium clusters down to nine atoms: structural and electronic contributions to melting.  

PubMed

First-principles Born-Oppenheimer molecular dynamics simulations of small gallium clusters, including parallel tempering, probe the distinction between cluster and molecule in the size range of 7-12 atoms. In contrast to the larger sizes, dynamic measures of structural change at finite temperature demonstrate that Ga7 and Ga8 do not melt, suggesting a size limit to melting in gallium exists at 9 atoms. Analysis of electronic structure further supports this size limit, additionally demonstrating that a covalent nature cannot be identified for clusters larger than the gallium dimer. Ga9, Ga10 and Ga11 melt at greater-than-bulk temperatures, with no evident covalent character. As Ga12 represents the first small gallium cluster to melt at a lower-than-bulk temperature, we examine the structural properties of each cluster at finite temperature in order to probe both the origins of greater-than-bulk melting, as well as the significant differences in melting temperatures induced by a single atom addition. Size-sensitive melting temperatures can be explained by both energetic and entropic differences between the solid and liquid phases for each cluster. We show that the lower-than-bulk melting temperature of the 12-atom cluster can be attributed to persistent pair bonding, reminiscent of the pairing observed in ?-gallium. This result supports the attribution of greater-than-bulk melting in gallium clusters to the anomalously low melting temperature of the bulk, due to its dimeric structure. PMID:23764996

Steenbergen, Krista G; Gaston, Nicola

2013-10-01

456

Catalyst Alloys Processing  

NASA Astrophysics Data System (ADS)

Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

Tan, Xincai

2014-10-01

457

X-ray study of the oxidation of liquid-gallium surfaces M. J. Regan,* H. Tostmann, and P. S. Pershan  

E-print Network

X-ray study of the oxidation of liquid-gallium surfaces M. J. Regan,* H. Tostmann, and P. S-Gan 52100, Israel Received 21 November 1996 The oxidation of liquid-gallium surfaces has been investigated on the order of 180 L of oxygen where 1 L 10 6 Torr s, a gallium oxide film with a well-defined thickness of 5

Grigoriev, Alexei

458

Amorphous metal alloy  

DOEpatents

Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

Wang, R.; Merz, M.D.

1980-04-09

459

Low activation ferritic alloys  

DOEpatents

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

Gelles, David S. (West Richland, WA); Ghoniem, Nasr M. (Granada Hills, CA); Powell, Roger W. (Pasco, WA)

1986-01-01

460

Measurement of Impact Ionization Coefficients in Gallium Nitride  

NASA Astrophysics Data System (ADS)

GaN has been recognized as a potential semiconductor for high temperature, high frequency and high power applications. Due to its wide bandgap, GaN exhibits high critical electric fields, which are suitable to sustain high breakdown voltages in power electronic devices. In order to obtain a good understanding of the breakdown characteristics of a power device, it is important to know the impact ionization coefficients of electrons and holes as a function of the electric field in the semiconductor. In this work, electron and hole impact ionization coefficients have been accurately measured in both GaN epitaxial layers grown on bulk GaN substrates and GaN epitaxial layers grown on Sapphire substrates using the pulsed electron beam induced current technique. Using Chynoweth's equation (alpha = a e-b/E), measurements for GaN epitaxial layer grown on bulk GaN substrates gave an aN value of 1.5x105 cm-1 and a bN value of 1.413x107 V/cm for the impact ionization coefficient of electrons in GaN at room temperature. For the impact ionization coefficients of holes in GaN, the values of aP and bP were found to be 6.4x105 cm-1 and 1.454x107 V/cm, respectively. An analytical solution of the form alpha = mEn for the variation of the impact ionization coefficients as a function of the electric field was derived, which is useful for analytical calculation of the breakdown voltages in GaN. For Chynoweth's equation (alpha = a e-b/E), measurements for GaN epitaxial layers grown on Sapphire substrates gave an aN value of 9.17x105 cm-1 and a bN value of 1.722x107 V/cm for the impact ionization coefficient for electrons at room temperature. For the impact ionization coefficients for holes at room temperature, the values of aP and bP were found to be 8.7x105 cm-1 and 1.464x107 V/cm, respectively. The values for both coefficients are larger than those measured for GaN grown on GaN substrates. The temperature dependence of the electron and hole impact ionization coefficients as a function of the electric field has been accurately measured for both GaN epitaxial layers grown on bulk GaN substrates and GaN epitaxial layers grown on Sapphire substrates. The impact ionization coefficients for both electrons and holes are observed to decrease with increasing temperature. This is consistent with the measured increase in the breakdown voltage with temperature for high voltage Schottky barrier diodes. This is an important observation demonstrating that stable power devices can be fabricated from Gallium Nitride. Electron Beam Induced Current (EBIC) technique was employed in order to understand the role of defects on the breakdown characteristics of GaN. The impact ionization coefficients for electrons and holes measured at the defective site were found to be higher than those measured at a non-defective site. These results indicate that the breakdown voltage of GaN devices can be reduced due to the presence of defects.

Ozbek, Ayse Merve

2011-12-01

461

a Study of P-Type Gallium Arsenide/aluminum Gallium Arsenide Multi-Quantum Well Materials for Normal Incidence Detection of Infrared Radiation.  

NASA Astrophysics Data System (ADS)

P-type GaAs/AlGaAs multiple quantum well materials were studied to evaluate the normal incidence detection of infrared radiation by these materials. Unlike the n -type quantum well materials being developed for imaging detector applications, the p-type materials have the capability for absorbing infrared radiation at normal incidence without the use of complicated gratings. This novel materials system is based on alternating epitaxial layers of gallium arsenide and aluminum gallium arsenide which form quantum wells in the energy band structure. The gallium arsenide layers are doped with acceptor impurities, such as beryllium or carbon. The selection of the layer thicknesses and compositions allows the tailoring of the optical properties of this multi-quantum well based material. The materials for this study were designed by the author using a comprehensive theoretical model of normal incidence absorption for valence band quantum well intersubband transitions. The electrical and optical properties of these designed materials were evaluated using infrared photoresponse measurements. Strong infrared photoresponse at normal incidence was confirmed in these materials. The intensity of this normal incidence photoresponse was studied as a function of the material design parameters. Comparing these results with theory, the optical transition from the heavy-hole ground state to second light-hole extended state in the continuum was determined to be the dominant transition for strong normal incidence absorption. This new design criterion was used to determine the optimum multi-quantum well structure for enhanced bound-to-continuum normal incidence absorption. In addition, for this material to achieve maximum detectivity the highest recommended acceptor doping level was assessed to be about 6 times 10^ {18} atoms/cm^3. This acceptor concentration would provide an infrared detector quantum efficiency of 63% in the optimized multi-quantum well structure. This high quantum efficiency for normal incidence absorption of infrared radiation makes the p -type quantum well materials a competitive choice for infrared detector applications.

Brown, Gail Jones

462

Origin of color centers in the flux-grown europium gallium garnet  

SciTech Connect

Europium gallium garnet (EuGG) single crystals were grown from fluxes with various contents. Optical absorption spectra of EuGG grown from a flux containing calcium show an additional band in the ultraviolet and blue regions of the spectra as compared to the case of a calcium-free flux. Moessbauer spectra of the samples grown from the fluxes with different additives show no signs of other valence states of the europium ions except for 3+. However, they indicate changes in the crystal field due to the entrance of additive ions. The nature of the additional absorption must be the same as that for calcium-doped gadolinium gallium garnet, i.e., anion vacancies. Moessbauer isotope shifts and quadrupole splitting for EuGG are determined.

Aleksandrovsky, A. S.; Arkhipkin, V. G.; Bezmaternykh, L. N.; Gudim, I. A.; Krylov, A. S. [L. V. Kirensky Institute of Physics, Akademgorodok, Krasnoyarsk 660036, Russia and Siberian Federal University, Krasnoyarsk 660079 (Russian Federation); Vagizov, F. [Department of Physics, Texas A and M University, College Station, Texas 77840 (United States)

2008-04-15

463

The Baksan Neutrino Observatory Soviet-American Gallium Solar Neutrino Experiment  

SciTech Connect

A radiochemical /sup 71/Ga-/sup 71/Ge experiment to determine the integral flux of neutrinos from the sun is currently under preparation at the Baksan Neutrino Observatory in the USSR. Measurements are scheduled to commence by late 1988 with 30 tonnes of metallic gallium. A fractional statistical accuracy of 18% is expected to be obtained after one year of operation if the solar signal obtained after one year of operation if the solar signal is 70 SNU, the flux expected from p-p neutrinos alone. While initial measurements are in progress, 30 additional tonnes of gallium will be installed in order to perform the full experiment with a 60-tonne target. 28 refs.

Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.V.; Avdeyev, A.V.; Belouska, Yu. I.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gavrin, V.N.

1988-01-01

464

Defect reactions in gallium antimonide studied by zinc and self-diffusion  

NASA Astrophysics Data System (ADS)

Extrinsic diffusion of zinc (Zn) in gallium antimonide (GaSb) under Ga-rich conditions was analyzed on the basis of the kick-out and the dissociative diffusion mechanism. It is concluded that the changeover of interstitial Zn to substitutional gallium (Ga) sites is mainly mediated by Ga interstitials ( IGa). Fitting of the Zn profiles provides the relative contributions of IGa to Ga diffusion. This contribution is lower than the directly measured Ga diffusion coefficient indicating that Ga diffusion in GaSb is rather mediated by Ga vacancies than by Ga interstitials even under Ga-rich conditions. This finding supports transformation reactions between native point defects that are confirmed by first-principles total-energy calculations. In addition Ga and Sb diffusion experiments under H22 atmosphere were performed to reconcile the controversial data on self-diffusion in GaSb published by Weiler et al. and Bracht et al.

Sunder, Kirsten; Bracht, Hartmut

2007-12-01

465

Fast neutron scattering on Gallium target at 14.8 MeV  

E-print Network

Benchmarking of evaluated nuclear data libraries was performed for $\\sim 14.8$ MeV neutrons on Gallium targets. The experiments were performed at China Institute of Atomic Energy(CIAE). Solid samples of natural Gallium (3.2 cm and 6.4 cm thick) were bombarded by $\\sim 14.8$ MeV neutrons and leakage neutron energy spectra were measured at 60$^{\\circ}$ and 120$^{\\circ}$. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL-3.1, ENDF/B-VII and JENDL-4.0 evaluated nuclear data libraries, except for the inelastic contributions around $E_{n} = 10-13$ MeV. All three libraries significantly underestimate the inelastic contributions. The inelastic contributions are further studied, using the Talys simulation code and the experimental spectra are reproduced reasonably well in the whole energy range by the Talys calculation, including the inelastic contributions.

Han, R; Chen, Z; Nie, Y; Liu, X; Zhang, S; Ren, P; Jia, B; Tian, G; Luo, F; Lin, W; Liu, J; Shi, F; Huang, M; Ruan, X; Ren, J; Zhou, Z; Huang, H; Bao, J; Zhang, K; Hu, B

2014-01-01

466

Fast neutron scattering on Gallium target at 14.8 MeV  

E-print Network

Benchmarking of evaluated nuclear data libraries was performed for $\\sim 14.8$ MeV neutrons on Gallium targets. The experiments were performed at China Institute of Atomic Energy(CIAE). Solid samples of natural Gallium (3.2 cm and 6.4 cm thick) were bombarded by $\\sim 14.8$ MeV neutrons and leakage neutron energy spectra were measured at 60$^{\\circ}$ and 120$^{\\circ}$. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL-3.1, ENDF/B-VII and JENDL-4.0 evaluated nuclear data libraries, except for the inelastic contributions around $E_{n} = 10-13$ MeV. All three libraries significantly underestimate the inelastic contributions. The inelastic contributions are further studied, using the Talys simulation code and the experimental spectra are reproduced reasonably well in the whole energy range by the Talys calculation, including the inelastic contributions.

R. Han; R. Wada; Z. Chen; Y. Nie; X. Liu; S. Zhang; P. Ren; B. Jia; G. Tian; F. Luo; W. Lin; J. Liu; F. Shi; M. Huang; X. Ruan; J. Ren; Z. Zhou; H. Huang; J. Bao; K. Zhang; B. Hu

2014-11-03

467

Synthesis, Structure, and Antiproliferative Activity of Three Gallium(III) Azole Complexes  

PubMed Central

As part of our interest into the bioinorganic chemistry of gallium, gallium(III) complexes of the azole ligands 2,1,3-benzothiadiazole (btd), 1,2,3-benzotriazole (btaH), and 1-methyl-4,5-diphenylimidazole (L) have been isolated. Reaction of btaH or btd with GaBr3 or GaCl3 resulted in the mononuclear complexes [GaBr3(btaH)2] (1) and [GaCl3(btd)2] (2), respectively, while treatment of GaCl3 with L resulted in the anionic complex (LH)2[GaCl4] (3). All three complexes were characterized by single-crystal X-ray crystallography and IR spectroscopy, while their antiproliferative activities were investigated against a series of human and mouse cancer cell lines. PMID:20721278

Zanias, Stergios; Papaefstathiou, Giannis S.; Raptopoulou, Catherine P.; Papazisis, Konstantinos T.; Vala, Vasiliki; Zambouli, Dimitra; Kortsaris, Alexandros H.; Kyriakidis, Dimitrios A.; Zafiropoulos, Theodoros F.

2010-01-01

468

Electrodeposition of Ga-O Thin Films from Aqueous Gallium Sulfate Solutions  

NASA Astrophysics Data System (ADS)

Ga-O based thin films were electrodeposited on fluorine-doped tin oxide (FTO)-coated glass substrate at room temperature from aqueous gallium sulfate solution with hydrogen peroxide (H2O2). Effects of different deposition parameters such as deposition voltage, amount of H2O2 and deposition time were investigated and presented. Nearly smooth and crack-free morphologies were attained at -1.0 V vs SCE deposition potential. As-deposited films showed O to Ga ratio of 2.0, which signified GaOOH formation. Thermal annealing of the as-deposited films in ambient air at 500-600 °C reduced the O/Ga ratio closer to stoichiometric gallium oxide (Ga2O3) and retained the morphology of Ga-O thin films. As-prepared films with ˜0.2 µm thickness had 80% transparency in the visible wavelength range.

Vequizo, Junie Jhon M.; Ichimura, Masaya

2013-07-01

469

Influence by trajectorial electron transport on anomalous ultrasound attenuation in high pure Gallium single crystal  

E-print Network

The anomalous propagation of longitudinal ultrasound with the frequencies of 70 and 150 MHz in the high pure Gallium single crystal at the weak external magnetic field (the magnetic field H perpendicular to the wave vector k) at the low temperature of 0.4 K was researched experimentally. The delayed ultrasonic signal, comparing to the main ultrasonic signal, is detected. The research on the new magneto-acoustic effects made it possible to find the temperature dependence of the frequency of collisions between the electrons and the thermal phonons in the high pure Gallium single crystal. It is found that the anomalous oscillations of propagation velocity of ultrasonic signal pulses and the signals, propagating by the way of the electron transport in the high pure type I superconductor, can be detected at the directions of the magnetic field H close to the magnetic field H parallel to the wave vector k.

Shepelev, Anatoly G; Filimonov, Genady D

2012-01-01

470

8-Quinolinolato Gallium Complexes: Iso-selective Initiators for rac-Lactide Polymerization  

PubMed Central

The synthesis and characterization of a series of 8-quinolinolato gallium complexes is presented, and the complexes are analogous to a series of aluminum complexes previously reported. The complexes have been shown to be active initiators for the ring-opening polymerization of rac-lactide. High degrees of polymerization control are demonstrated, as exemplified by the linear evolution of molecular weight as the polymerization progresses, narrow polydispersity indices, and molecular weights corresponding to those predicted on the basis of initiator concentration. Some of the initiators show iso-selective polymerization of rac-lactide, with Pi = 0.70. The polymerization rates have been monitored, and the pseudo first-order rate constants are compared to those of analogous aluminum compounds. The 8-quinolinolato gallium initiators show rates approximately 3 times higher than those of the series of aluminum compounds, while maintaining equivalently high iso-selectivity (Pi = 0.70) and polymerization control. PMID:24138079

2013-01-01

471

Altered biodistribution of gallium-67 in a patient with aluminum toxicity treated with desferoxamine  

SciTech Connect

Markedly altered biodistribution of ({sup 67}Ga)citrate was observed in a 66-yr-old hemodialysis patient imaged at 48 hr postinjection. A review of the patient's hospital records revealed toxic serum levels of aluminum, treated with the chelating agent desferoxamine. Based on what is known about the biologic interactions between gallium, aluminum, transferrin, and desferoxamine, we believe that both toxic serum aluminum levels and desferoxamine therapy may cause altered biodistribution on ({sup 67}Ga)citrate scintigraphy.

Brown, S.J.; Slizofski, W.J.; Dadparvar, S. (Hahnemann University Hospital, Philadelphia, PA (USA))

1990-01-01

472

Activation and stabilization of gallium arsenide anode in an aqueous photoelectrochemical cell  

Microsoft Academic Search

The formation of a porous layer on the surface of gallium arsenide anode, n-GaAs, increases photogenerated currents significantly. This layer was formed as a result of an anodic polarization of illuminated n-GaAs in acidified chloride electrolytes. The formation of the porous layer was confirmed by scanning electron microscopy micrographs. The porous layer increases the reflectivity of GaAs to light, thus

Siham Y. Alqaradawi; Amina S. Aljaber; Mahmoud M. Khader

2003-01-01

473

Radiochemical study of ruthenium adsorption from acid solution onto gallium arsenide surfaces  

Microsoft Academic Search

A radiochemical study of the adsorption of ruthenium ions onto GaAs surfaces is performed using solutions labeled with °⁶Ru{sup 3+}. The coverage-time characteristics have been determined for a variety of conditions, including changes in the etching procedure, the Ru{sup 3+} concentration, the solvent for RuClâ, and the incident light intensity. Additional gallium and arsenic analyses combined with transmission electron microscopy

Roland. Schlesinger; Peter. Janietz; Karl Heinz. Heckner; Peter. Rotsch

1990-01-01